A mathematical model for the evolution of, and deposition from, a thin particle-laden droplet on a fully flooded porous substrate undergoing simultaneous evaporation and imbibition is formulated and analyzed. While the physical mechanisms driving evaporation and imbibition are rather different, it is found that there are several qualitative and quantitative similarities in the behavior of the droplet as it loses mass to its environment. Not only are these results of theoretical interest, but they are also relevant to a wide variety of practical applications that would benefit from an improved ability to predict and/or control the pattern of the final deposit left on the substrate.

[Phys. Rev. Fluids 11, 093601] Published Mon Sep 14, 2026

Self-rewetting fluids that exhibit a quadratic dependence of surface tension with temperature result in thermocapillary flows that are markedly different from normal fluids. However, their behavior in the presence of an insoluble surfactant is not yet fully understood. We consider an inertialess surfactant-laden self-rewetting fluid film flowing down a heated cylinder under gravity, by deriving a reduced-order model under the lubrication approximation. A systematic linear stability analysis of our models indicates the stabilizing influence of surfactants at small wavenumbers, whereas conventional (anomalous) thermocapillarity is destabilizing (stabilizing) at mid-wavenumbers.

[Phys. Rev. Fluids 11, 094002] Published Mon Sep 14, 2026

What if we could learn not just which mode structures dominate a flow, but how they actually drive fluid-particle transport? This paper bridges Eulerian modal analysis and Lagrangian coherent structures by introducing modal-trajectory uncertainty, a sensitivity-based framework that reveals where specific modes influence particle trajectories and finite-time Lyapunov exponent (FTLE) structures. Across cylinder wakes, an oscillating-foil wake, and turbulent channel flow, the approach reveals interactions spanning vortex shedding, shear-layer instabilities, and large-scale turbulent motions.

[Phys. Rev. Fluids 11, 094902] Published Fri Sep 11, 2026

Extreme events in turbulent flows are rare, abrupt bursts in the system observable, posing significant challenges for prediction and control due to their nonlinearity and high dimensionality. Here, we present a predominantly data-driven framework for their suppression, combining dimensionality reduction through symmetry-aware autoencoders and data-driven clustering in the latent space of the former for the identification of precursors. A control law defined in this latent space substantially reduces the frequency and intensity of extreme events, by up to 99.4% in a canonical chaotic flow, demonstrating scalability to higher-Reynolds-number regimes and practical control limitations.

[Phys. Rev. Fluids 11, 093902] Published Thu Sep 10, 2026

Gas transport in nanoporous media is strongly influenced by surface roughness, wettability, and molecular confinement, yet these effects are difficult to incorporate consistently into continuum-scale descriptions. We develop a molecular-based apparent permeability model that combines roughness corrections derived from molecular dynamics simulations with confinement and fluid–solid interaction effects. The model provides a systematic framework for disentangling these nanoscale mechanisms and predicting their combined influence on apparent permeability.

[Phys. Rev. Fluids 11, 094201] Published Thu Sep 10, 2026

Fractal flocs occur in sediments, aerosols, and many particulate flows, yet their unsteady hydrodynamic inertia is often approximated using equivalent-sphere or free-draining models. We compute the added-mass and added-moment-of-inertia tensors of large ensembles of porous flocs over a range of sizes and fractal dimensions. The results reveal morphology-dependent anisotropy, systematic departures from simple approximations, and decreasing floc-to-floc variability with increasing size. We provide compact stochastic closures that can be used in large-scale simulations.

[Phys. Rev. Fluids 11, 094303] Published Thu Sep 10, 2026

Existing temporal super-resolution methods struggle to reconstruct three-dimensional turbulent flows across large time gaps, often losing coherent vortical structures and giving flow-specific performance. We introduce ResSE-LSTM, an attention-enhanced convolutional LSTM (long short-term memory) framework that recovers intermediate 3D velocity fields from two sparse snapshots and remains robust to noisy inputs. A Kolmogorov-scale temporal parameter, Π𝑡, unifies performance across Reynolds numbers. The model recovers Reynolds stresses and coherent structures up to Π𝑡 ≤ 4, versus Π𝑡 ≤ 0.8 for a CNN baseline, enabling reliable reconstruction from sparse simulations and measurements.

[Phys. Rev. Fluids 11, 094601] Published Thu Sep 10, 2026

Liquid films flowing along fibers can exhibit distinct dripping and jetting regimes, yet the differences in bead-formation mechanisms and the transition between these regimes have received limited attention. By combining experiments with a theoretical model, we discuss the mechanisms governing bead formation in both regimes and introduce a method for identifying and predicting the transition range across different fiber-nozzle geometries. This work advances the fundamental understanding of bead formation and regime transitions in film flows on fibers.

[Phys. Rev. Fluids 11, 094001] Published Wed Sep 09, 2026

In granular films, where grains bridge the two interfaces of a soap film, the liquid pressure controls the transition from bursting to a jammed state. Even more, a single bursting event combines liquid- and solid-like mechanical responses. By identifying both an effective surface viscosity governing the early liquid-like regime and an internal dissipation controlling the late fracture dynamics, we provide a unified physical picture and highlight the differences between granular films and granular rafts. The concepts introduced here may prove relevant for a broad range of systems in which particles and interfaces interact, from particle-laden foams to biological or bio-inspired membranes.

[Phys. Rev. Fluids 11, 094301] Published Tue Sep 08, 2026

Thermal diffusivity measurements in a sheared particle-fluid suspension are performed in a Taylor-Couette cell with outer cylinder rotation. The enhancement in diffusivity follows a power law with Peclet number with an exponent of 0.5 for Peclet numbers below 700 at all volume fractions studied (0.14, 0.22, 0.30 and 0.36). The data do not fit existing theory and are consistent with a model that assumes the formation of a particle-free fluid layer near the inner cylinder which causes deviation from an initially linear behavior at low particle Peclet numbers.

[Phys. Rev. Fluids 11, 094302] Published Tue Sep 08, 2026

This study introduces a novel approach for generating isolated vortex gusts in both computational and experimental settings. Utilizing a symmetric airfoil undergoing simultaneous heaving and pitching, this method delivers coherent vortices while minimizing persistent wake disruption downstream. The result is a customizable approach allowing precise, systematic control over vortex strength, orientation, and position.

[Phys. Rev. Fluids 11, 094702] Published Tue Sep 08, 2026

This study investigates the formation of the helical vortex rope in a Francis hydropower turbine by treating it as an unstable vortex breakdown mode in a simplified laminar flow. The vortex rope emerges through a supercritical Hopf bifurcation from an axisymmetric base flow in the draft tube. Without wall friction, a central recirculation zone develops, revealing subcritical solutions and hysteresis under partial-load conditions. The work describes the cyclic formation and collapse of the recirculation bubble as the helical vortex evolves. As flow approaches nominal load, the steady solution branch undergoes a transcritical bifurcation at finite Reynolds number.

[Phys. Rev. Fluids 11, 094701] Published Thu Sep 03, 2026

Surface tension is frequently measured with the pendant drop method, while the ambient humidity is usually an afterthought. With carefully calibrated experiments and detailed numerical simulations, we show that evaporative cooling lowers the drop temperature by up to 9.5 K which in turn raises the measured surface tension by more than 1 mN/m. Evaporation-driven and Marangoni-induced flows additionally deform the drop, but only marginally. A passive humidity control removes these artifacts entirely and reveals the shallow minimum in the surface tension of aqueous 1,2-hexanediol mixtures.

[Phys. Rev. Fluids 11, 094901] Published Thu Sep 03, 2026

Lifting surfaces operating at aerodynamically low Reynolds numbers often have laminar separation bubbles (LSBs) whose characteristics can significantly affect performance. We investigate the effect of localized surface roughness, which might form due to manufacturing, local contamination, damage or icing, on LSBs. We find that the localized roughness eliminates downstream laminar separation and modifies the LSB topology and dynamics over a substantial spanwise region extending well beyond the roughness itself. The associated effect on aerodynamic performance is considerably greater than would be expected based solely on the relative spanwise extent of the localized roughness.

[Phys. Rev. Fluids 11, 093901] Published Tue Sep 01, 2026

Compared with a static liquid film, gas jet impingement on a flowing liquid metal film produces a shallower cavity and a strongly asymmetric profile through upstream liquid accumulation. Counter-current coupling upstream and co-current coupling downstream cause the wave-amplitude response to jet momentum to weaken upstream but strengthen downstream as the liquid Reynolds number increases. Under pulsating jets, an attenuation coefficient correlates wave amplitude with jet momentum and characterizes a pronounced spatial asymmetry in momentum transfer. These findings clarify how gas jets influence the liquid metal film flow and provide a reference for the design of liquid metal divertors.

[Phys. Rev. Fluids 11, 094801] Published Tue Sep 01, 2026

This article presents a simple to implement algorithm for detecting strong cabbeling in stratified fluids with a nonlinear equation of state. The algorithm is used to identify the manner in which the arrested development of the Rayleigh-Taylor instability occurs in the strongly cabbeling regime.

[Phys. Rev. Fluids 11, 084505] Published Mon Aug 31, 2026

Large staggered roughness elements in the entrance region of a subcritical channel flow generate intense turbulent eddies that gradually break down as the flow progresses into the downstream smooth channel (SC) of the configuration studied here. This flow combines several sources of complexity: surface roughness, a rough-to-smooth step change and relaminarization. The characteristics of the turbulence decay along the SC centerline agree reasonably well with those of homogeneous isotropic turbulence. Owing to the slow rate of relaminarization, the Nusselt number averaged over large streamwise distances in the SC remains close to that of an equivalent fully developed turbulent channel flow.

[Phys. Rev. Fluids 11, 084611] Published Mon Aug 31, 2026

Vortex reconnections are fundamental to quantum fluids. They are reconnections of quantum vortices defined by a topological change and irreversible energy transfer given by universal scaling laws, leading to quantum turbulence. We generalize this mechanism by studying reconnections of extra-dimensional quantum vortices. We find a new range of vortex interactions depending on their initial orientation – a four-dimensional generalization to the known three-dimensional case; vortex interactions with no reconnections; and a new class reconnection that keeps the same scaling law with no energy transfer, suggesting a form of reversible reconnection not allowed in three-dimensional systems.

[Phys. Rev. Fluids 11, 084701] Published Mon Aug 31, 2026

We study flow past V-formations of cylinders, inspired by migratory birds’ flight, examining how formation angle affects the drag of both individuals and the group. Using particle image velocimetry in a water tunnel, we evaluate the impact of changing angles on complex wake-wake/wake-body interactions, quantifying mean and fluctuating quantities, and analyzing vortex dynamics. We find that members with streamwise overlap experience major reductions in the drag force compared to a solo cylinder. Our study establishes a baseline for probing flow past groups of complex bodies (like drones) and demonstrates how optimizing formations can achieve desired performance goals, such as minimum drag.

[Phys. Rev. Fluids 11, 084702] Published Mon Aug 31, 2026

We present a numerical study of shock-induced dispersal in dense, flexible fiber curtains using a coupled discrete element method–computational fluid dynamics (DEM–CFD) approach. The fiber curtains exhibit distinct particle dynamics compared to spherical particle curtains. Increasing the fiber aspect ratio and reducing flexibility enhance geometric interlocking and prolong clustering, thereby increasing resistance to shock propagation. Finally, we modify a scaling law using an effective fiber aspect ratio to predict the temporal evolution of curtain expansion, accounting for fiber elongation and significant bending deformation.

[Phys. Rev. Fluids 11, 084302] Published Fri Aug 28, 2026

Vertical accelerations can amplify small free-surface disturbances into strongly nonlinear sloshing through parametric resonance, yet the resulting regimes remain poorly characterized in horizontal cylindrical tanks. While the classical Mathieu equation predicts the onset of parametric instability, here, high-speed experiments, combined with data-driven modal analysis and classification, reveal nonlinear responses that develop beyond the instability threshold. The resulting dimensionless regime maps organize stable, longitudinal, breaking, and mixed-mode dynamics across different fill levels, exposing the rich flow phenomenology surrounding the primary parametric-instability region.

[Phys. Rev. Fluids 11, 084804] Published Fri Aug 28, 2026

This paper uses direct numerical simulations to systematically investigate supersonic flows in a bent pipe with a developing turbulent boundary layer and a core flow region. The results reveals that boundary layers experience intricate flow patterns at different azimuthal angles: secondary flows that drives the streaks move from the lower to the upper side; separation triggered by the combined effects of the adverse pressure gradient and flow deceleration on the upper wall; and the increase of the Görtler instability on the lower wall inducing the clustering and uplift of low-momentum fluids, the presence of Görtler-like vortices, and the baroclinic effect of turbulent transport processes.

[Phys. Rev. Fluids 11, 083401] Published Thu Aug 27, 2026

Turbulent transport in large-eddy simulations relies on subgrid-scale (SGS) closures, yet conventional models typically assume that SGS stresses are uniquely determined by the resolved flow. We introduce a conditional diffusion model that learns the conditional distribution of SGS stresses from high-resolution atmospheric boundary layer simulations. By representing conditional variability rather than a single deterministic mapping, the proposed framework accurately reproduces SGS stress statistics, generalizes across unseen stability regimes and grid resolutions, and provides a new probabilistic framework for SGS turbulence modeling.

[Phys. Rev. Fluids 11, 084610] Published Wed Aug 26, 2026

Metal-pad-roll instabilities limit the safe and efficient operation of aluminum reduction cells, yet laboratory-scale models fall outside the assumptions of most existing theories. We develop an analytical stability theory for small rectangular two-layer cells that captures finite-depth, viscous, and capillary effects, including a parameter-free description of interfacial-wave damping. Validated against direct numerical simulations and experiments, the theory provides quantitative benchmarks for designing and interpreting small-scale MHD experiments and multiphase simulations.

[Phys. Rev. Fluids 11, 084803] Published Wed Aug 26, 2026

We introduce a simple droplet generation technique that rapidly stretches a liquid ligament on both quiescent and vibrating baths. By systematically varying the stretching distance and the radius of the cylindrical probe used to form the ligament, we map the parameter space in which the ligament pinches off and collapses into a single droplet. The resulting droplet size follows the volume-conservation scaling $R\sim a^{2/3}{L}^{1/3}$ , with excellent reproducibility (radius variation below 5%).

[Phys. Rev. Fluids 11, L082001] Published Wed Aug 26, 2026

Polymer diffusive instability (PDI) provides a unique route to instability in viscoelastic flows at vanishing Reynolds numbers, yet how realistic wall conditions modify its behavior remains unclear. Here, we show that wall slip regulates PDI in viscoelastic Poiseuille flows by altering the dominant instability pathway. Increasing slip weakens the near-wall PDI-1 mechanism and favors a shear-driven PDI-2 regime. Combining linear stability analysis and direct numerical simulations, we reveal the energy-transfer processes underlying this slip-induced transition and provide new insight into controlling polymer-flow instabilities.

[Phys. Rev. Fluids 11, 083905] Published Mon Aug 24, 2026

Granular materials dissipate energy through frictional rearrangement and dissipative collisions, yet these mechanisms are often entangled or partially neglected in continuum models. We develop a unified viscoelastic–viscoplastic framework that links the coefficient of restitution $e$ directly to continuum viscosities while preserving the established $\mu (I)$ rheology during plastic flow. Implemented within the material point method, the model reproduces the steady-state Bagnold solution, wave propagation, impact, dynamic reposing behavior, and vibration-induced pattern formation. These results emphasize that restitution must be embedded correctly to capture granular flow dynamics accurately.

[Phys. Rev. Fluids 11, 084301] Published Mon Aug 24, 2026

Wall-attached motions leave an intermittent footprint on the near-wall flow, but conventional coherence analyses reveal only its time-averaged behavior. Using synchronized two-point hot-wire measurements in a high-Reynolds-number turbulent boundary layer, we develop a wavelet-based framework that resolves this wall imprint in time and scale while recovering established mean coherence scaling. The results show that the characteristic persistence scale grows with wall distance even as coherence at that scale weakens, and that strongly wall-imprinted events exhibit systematic wall-normal changes in scale-local energy transfer and energy distribution.

[Phys. Rev. Fluids 11, 084609] Published Mon Aug 24, 2026

Numerical studies of viscoelastic Stokes flow often regularize the stress singularities predicted by the Oldroyd-B model, obscuring their underlying structure. We introduce an efficient FFT-based projection solver for incompressible flow and validate it in the classical four-roll mill. By analyzing the polymeric stress directly in Fourier space, we quantify its power-law scaling with resolution and determine the critical Weissenberg number for steady-state convergence without adding artificial stress diffusion.

[Phys. Rev. Fluids 11, 084901] Published Mon Aug 24, 2026

Resolvent analysis is a cornerstone tool for predicting how flows respond to external forcing, but for unsteady flows the choice of linear operator is not obvious. The common mean-flow resolvent, linearized about the time-averaged flow, can misidentify the dominant receptivity mechanisms, whereas the statistically optimal mean resolvent correctly captures physically relevant phenomena such as the vortex pairing in jets presented here. This work introduces a projection method that enables mean resolvent analysis at low computational cost without resorting to adjoint equations about the unsteady attractor, thereby opening a path toward more complex flows.

[Phys. Rev. Fluids 11, 083903] Published Mon Aug 17, 2026

Reactive fronts in porous media are often destabilized by concentration dependent viscosity of the constituent fluids, leading to viscous fingering. These processes are known to be strongly influenced by hydrodynamic dispersion, originating from incomplete mixing at the pore scale. Yet, their impact and the resulting instabilities remain poorly understood. This study combines transient and quasi-steady-state linear stability analysis to reveal how hydrodynamic dispersion and diffusivity contrasts govern the growth and onset of instabilities, providing new physical insights, with potential applications in contaminant remediation, enhanced oil recovery, and carbon sequestration.

[Phys. Rev. Fluids 11, 083904] Published Mon Aug 17, 2026

Classical similarity theory describes the far field of a laminar jet, but not how a finite Poiseuille inlet loses its memory and reaches that state. We develop a self-consistent two-mode analytical model that predicts this pre-asymptotic evolution without empirical fitting. The theory uncovers a universal Reynolds-scaled centerline decay and shows that the transition length grows linearly with Reynolds number, while reproducing full velocity profiles for both round and slot jets in close agreement with Navier–Stokes simulations.

[Phys. Rev. Fluids 11, 084101] Published Mon Aug 17, 2026

Air curtains restrict buoyancy-driven exchange through building doorways, but sealing effectiveness saturates near about 80 to 85% and the transport pathways fluid takes to leak through have remained unclear. We combine large-eddy simulation with Lagrangian particle tracking to follow individual fluid parcels, classifying their trajectories into three pathways: a gravity current active only before the curtain establishes, and two turbulent-entrainment routes that dominate afterward. Once the curtain is established, the residual leakage is shown to be governed by entrainment at the jet interface rather than by buoyancy.

[Phys. Rev. Fluids 11, 084504] Published Mon Aug 17, 2026

The velocity law of the wall is a well-known law for wall turbulence. In compressible turbulence, the temperature law of the wall is also of interest, but its overall accuracy is inferior to its velocity counterpart. We propose to construct the compressible law of the wall for heat energy using total enthalpy. A semilocal total enthalpy transformation of no fitted parameters is constructed for channel flows, which is structurally analogous and comparable in accuracy to the Trettel–Larsson velocity transformation. This new transformation can potentially serve as a wall model for energy equations to accurately predict the enthalpy or temperature in compressible turbulence.

[Phys. Rev. Fluids 11, 084608] Published Mon Aug 17, 2026

The offshore wind industry is expanding in deep, seasonally stratified waters, where infrastructure-induced mixing may alter ocean dynamics and ecosystems. We present the first fully structure-resolved direct numerical simulations of stratified flow past a vertical cylinder as an idealized model for flow interactions with offshore wind foundations. We identify two distinct wake regimes: a weakly stratified regime characterized by a narrow turbulent wake, and a strongly stratified regime characterized by thermocline-spanning recirculation cells and stationary internal waves, providing a new mechanism for far-field energy transport and a possible explanation for wake persistence discrepancies.

[Phys. Rev. Fluids 11, 084802] Published Mon Aug 17, 2026

This study investigates nonaxisymmetric shape oscillations of an inviscid droplet. A highly accurate Galerkin framework is extended to fully three-dimensional droplet oscillations, and modal coupling is examined for different initial configurations, beginning with four nonaxisymmetric initial shapes (see Figure). The results show that the droplet keeps the symmetries of its initial shape and velocity throughout the oscillation. Only those modes that exhibit all symmetries of the initial configuration are excited. Conversely, modes which violate the symmetries are not excited.

[Phys. Rev. Fluids 11, 083602] Published Fri Aug 14, 2026

In preparation for the DRESDYN precession dynamo experiment, we numerically investigate how wall material properties impact the growth of magnetic modes driven by a precessing flow. We identify two oscillating magnetic modes - dipolar and quadrupolar – whose competition explains the drastic changes in dynamo thresholds for different types of boundaries. For given hydrodynamic parameters, these modes are paramount for a comprehensive understanding of all electromagnetic configurations, including the realistic modeling of the upcoming first liquid sodium campaign.

[Phys. Rev. Fluids 11, 083701] Published Fri Aug 14, 2026

Gravity-driven thin films laden with soluble surfactants play a central role in coating technologies and microfluidic systems, where reduced-order models are widely used to predict interfacial dynamics. Some weighted-residual formulations, however, introduce spurious interfacial mass growth, violating total surfactant conservation. We resolve this inconsistency by developing a conservative weighted-residual model that consistently couples wall slip, adsorption-desorption, and the Marangoni effect while rigorously preserving total surfactant mass. The resulting framework provides physically consistent predictions of instability onset, nonlinear wave dynamics, and surfactant transport.

[Phys. Rev. Fluids 11, 084004] Published Fri Aug 14, 2026

Wind-driven wave evolution is commonly viewed as a two-stage process: initial wave growth followed by frequency downshift. Here, we reveal a previously unrecognized intermediate stage in the evolution of capillary–gravity waves under wind forcing and dissipation. This stage is characterized by coupled three- and four-wave near-resonant interactions that generate new wave components, broaden the spectrum, and may reduce total wave energy. These findings constitute a major step forward in understanding the evolution of wind waves from small ripples (2.5 cm) to larger-scale waves.

[Phys. Rev. Fluids 11, 084801] Published Fri Aug 14, 2026

Interfacial Hele-Shaw flows often involve fingering instabilities, tip-splitting phenomena and striking pattern formations. This study revisits a simplified model that characterizes the complexity of these fingering patterns and identifies some universal features. We test this model using fully nonlinear numerical simulations and find that it is very effective at predicting near-universal properties of the fingering patterns for one-phase flows with a sufficiently small surface tension parameter. For larger values of this parameter and for two-phase flows, there are discrepancies between the model and our observations, which we explain by studying the morphology of the advancing fingers.

[Phys. Rev. Fluids 11, 084003] Published Thu Aug 13, 2026

Ocean Alkalinity Enhancement (OAE) is a promising marine carbon dioxide removal strategy involving the release of alkaline particles into the ocean. However, its effectiveness depends on how these particles disperse. This study uses high-resolution simulations to show that collective convective instabilities, rather than individual Stokes settling, fundamentally govern particle settling. These instabilities can accelerate vertical particle transport by up to two orders of magnitude, significantly limiting horizontal spread and surface residence time. These fundamental fluid-dynamic constraints provide essential guidance for optimizing future OAE deployments.

[Phys. Rev. Fluids 11, 084503] Published Thu Aug 13, 2026

Small-scale intermittency is conventionally modeled by power laws of higher-order moments, which include both kinematic and turbulence-driven effects. By using Kullback-Leibler divergence relative to a Gaussian random field, we isolate purely turbulence-induced intermittency, which scales logarithmically with the Taylor Reynolds number. This reveals an emergent symmetry between the turbulence intermittency of dissipation rate and enstrophy, showing that enstrophy appears more intermittent for purely kinematic reasons. The work establishes an information-theoretic framework for characterizing the intermittency and uncertainty of small-scale turbulence.

[Phys. Rev. Fluids 11, 084605] Published Thu Aug 13, 2026

Mixed convection for heavy liquid metals is still $terra$ $incognita$ in many aspects, because of the complex flow mechanism, strong thermal diffusivity, and optical opacity. Understanding the flow organization is key to turbulence research and practical engineering. We use high-fidelity scale-resolving numerical simulations to explore the unique large-scale longitudinal roller structures in mixed convection, while also considering the low Prandtl number effect of heavy liquid metals. A new physical interpretation for the slope modulation phenomenon of the mean velocity profile is established, which is expected to give new insights into wall function modeling in mixed convection.

[Phys. Rev. Fluids 11, 084606] Published Thu Aug 13, 2026

Most studies of turbulent wall pressure reduce its dynamics to wavenumber-frequency spectral descriptions, leaving the instantaneous, spatially evolving pressure field largely inaccessible to experiments and prohibitively expensive simulations. We introduce a probabilistic generative approach that reconstructs full spatiotemporal wall-pressure fields from sparse surface measurements and a low-cost mean-pressure descriptor. Combining patchwise neural representations with latent diffusion, the model adapts to unseen sensor layouts and pressure-gradient regimes without retraining. It recovers coherent structures, temporal evolution, and key turbulence statistics.

[Phys. Rev. Fluids 11, 084607] Published Thu Aug 13, 2026

When gravity currents converge inward, such as sea breezes closing in around an island or lake, their collision unfolds very differently from the situation when two gravity currents meet head-on. Using high-resolution three-dimensional simulations, this study reveals, for the first time, how such collisions generate turbulence: vorticity arises primarily through tilting of azimuthal vorticity rather than through the stretching mechanism as seen in planar collisions. The resulting eddy diffusivity data support existing mesoscale-model parameterizations used to represent gravity current collision events in atmospheric and oceanic models.

[Phys. Rev. Fluids 11, 083801] Published Wed Aug 12, 2026

A millimetric droplet may walk across the surface of a vibrating liquid bath, self-propelled by its own wave field. This pilot-wave hydrodynamic system has provided the basis for the field of hydrodynamic quantum analogs, the goal of which is to redefine the boundaries between classical and quantum systems. We here deepen our understanding of pilot-wave hydrodynamics through consideration of its energetics, evaluation of the partitioning between droplet and wave energies. Photo credit: Pedro Nachbin.

[Phys. Rev. Fluids 11, 084002] Published Wed Aug 12, 2026

Previous theoretical works showed that, in double-diffusion regimes, the onset time and mixing velocity of convective fingers are controlled by a dynamic density jump across stratified layers. Here, we experimentally validate these scalings by analyzing differential diffusion-induced convection in horizontal stratifications within a Hele-Shaw cell. Using a wide range of solute combinations and concentrations, we vary the two key parameters of the problem: the diffusion coefficient and buoyancy ratios. We show that, in both double-diffusive and diffusive-layer-convection regimes, convective dynamics are governed by dynamically generated local adverse density jumps.

[Phys. Rev. Fluids 11, 084502] Published Tue Aug 11, 2026

Classical shell models of turbulence fail to reproduce the dual energy–enstrophy cascade of two-dimensional flows because they predict the wrong equilibrium spectra. Introducing a hierarchical spatial organization across scales restores the correct equilibrium scaling and leads to a statistically stationary dual cascade. The resulting model consistently captures both the equilibrium properties and the nonequilibrium cascade dynamics of two-dimensional turbulence.

[Phys. Rev. Fluids 11, 084604] Published Tue Aug 11, 2026

We report direct experimental observations of self-sustaining CH4–air flames rotating along the edge of an unheated circular Hele-Shaw cell, extending beyond previous studies in which such flames were observed only under external heating. Formed under fuel-rich conditions, these flames exhibit stable traveling-wave behavior, with edge velocities exceeding nominal laminar flame speeds and a structure comprising both premixed and diffusion branches. The rotation arises from a balance between local flame speed, flow, and wall heat loss. Parametric studies have identified regimes of single and multiple rotating waves, as well as transitions to ring flames or extinction under extreme conditions.

[Phys. Rev. Fluids 11, 083201] Published Mon Aug 10, 2026

We investigate subcritical turbulence in plane Couette flow using a finite-amplitude columnar vortex instead of the conventional Lundbladh-type perturbation. We show that, although the perturbation modifies the turbulent structure, the key characteristics of subcritical turbulence remain unchanged. The figure illustrates the breakdown of the columnar vortex into tripolar and quadrupolar structures in unstratified and stably stratified flows. The columnar vortex breakup provides a new mechanism for streamwise streak formation.

[Phys. Rev. Fluids 11, 083301] Published Mon Aug 10, 2026

We revisit the classical hoop-stress mode (HSM) instability in viscoelastic Taylor-Couette flow using the FENE-P model. We show how finite polymer extensibility modifies the onset of the hoop-stress mode for a range of gap width ratios. By systematically comparing linear stability predictions with experiments and direct numerical simulations, we identify where the model succeeds and where its limitations emerge and what are the possible reasons for the discrepancies. We also compare our linear stability results with an augmented Pakdel–McKinley criterion that incorporates finite extensibility and finite gap effects.

[Phys. Rev. Fluids 11, 083302] Published Mon Aug 10, 2026

Low-flow-rate instabilities in vaneless diffusers remain a long-standing challenge in turbomachinery, with the roles of core-flow dynamics and boundary layers still debated. Using a hierarchy of linear stability analysis and two- and three-dimensional URANS simulations, we identify two distinct instability mechanisms and trace them back to their physical origins. The low-flow-rate instability is shown to arise from a two-dimensional inviscid core-flow mechanism, while a new instability, associated with inlet modulation and three-dimensional flow features, is reported at high flow rates.

[Phys. Rev. Fluids 11, 083902] Published Mon Aug 10, 2026

Reactive solute transport in open-channel flows is central to understanding contaminant migration in rivers, wetlands, and engineered waterways, but the combined influence of wind-induced shear, porous-bed resistance, and wall absorption has remained unresolved. This study introduces a generalized dispersion model that captures the coupled transient effects of those three influences through analytical transport coefficients and concentration distributions, validated by Brownian dynamics simulations. The findings reveal how wind direction governs pollutant dispersion, retention, and removal, and provides a predictive framework for layered environmental flows.

[Phys. Rev. Fluids 11, 084501] Published Mon Aug 10, 2026

In this work, we analyze two-dimensional turbulence in a Galerkin-truncated system with pseudo-logarithmic and random mode selection in Fourier space. The results confirm the presence of the double energy cascade ($k^{-5/3}$ and $k^{-3}$) and show how anisotropy influences the organization of vorticity without altering universal scaling laws. Finally, particle pair dispersion follows Richardson superdiffusion (${\ell }^2(t)\sim t^3$), demonstrating that preserved spectral interactions sustain turbulent transport.

[Phys. Rev. Fluids 11, 084603] Published Mon Aug 10, 2026

Capillary attachment is a fundamental phenomenon in microengineering, yet the lack of comprehensive theories makes it difficult to predict a pendant drop’s particle-lifting capability. We investigate the critical roles of stability in this process, specifically addressing how to maximize lifting capacity. Our work establishes the theoretical framework required to successfully lift particles in practical applications.

[Phys. Rev. Fluids 11, 084001] Published Fri Aug 07, 2026

Direct numerical simulations reveal the orientation and transport of spherical, spheroidal, and rod-like gyrotactic microswimmers in three-dimensional turbulence. Strongly gyrotactic swimmers preferentially align with the vertical, while weakly gyrotactic swimmers are nearly isotropic. Rod-like swimmers are more strongly affected by fluid shear and align with the principal strain direction. Orientation correlations depend on the gyrotactic response time, and all shapes transition from ballistic to diffusive transport. A reduced two-dimensional model for spherical swimmers reproduces the key statistics.

[Phys. Rev. Fluids 11, 084602] Published Tue Aug 04, 2026

The ability of red blood cells to deform under shear flow is critical to cardiovascular function, yet capturing their complex fluid-structure interactions remains challenging. We extend a perturbative approach to capture cellular enucleation, and probe the emergence of shape instabilities under shear flow. This method isolates how a cell’s initial orientation, membrane mechanics, and viscosity contrast drive morphological instabilities, such as stomatocytes and trilobes. Ultimately, this framework provides a baseline for understanding how disorders like sickle cell disease and malaria compromise cells dynamics.

[Phys. Rev. Fluids 11, 083601] Published Mon Aug 03, 2026

Rayleigh-Taylor mixing is important in natural phenomena and engineering applications, but limited spatial resolution in practical experiments and simulations constrains studies of this mixing process. Resolution-limited fields preserve only large-scale features such as mean profiles and mixing widths, but fail to resolve small-scale structures, resulting in lower fluctuation variance and higher apparent mixedness. Convolutional neural network (CNN) based superresolution reconstructs multiscale flow fields and recovers mixedness evolution, with robust generalization across unseen phases and flow parameters.

[Phys. Rev. Fluids 11, 083901] Published Mon Aug 03, 2026

The turbulent flow beneath a water surface is difficult to measure directly, yet it governs important processes such as mixing and air–water gas exchange. We show that the SHallow REcurrent Decoder (SHRED), a lightweight recurrent neural network, can reconstruct subsurface turbulent flow fields using only three sparse measurements of the surface height. The method performs well on both numerical simulations and laboratory experiments, highlighting its potential for future remote sensing of rivers and other free-surface flows.

[Phys. Rev. Fluids 11, 084601] Published Mon Aug 03, 2026

We study how viscoplastic filaments retract and break. Unlike Newtonian liquids, viscoplastic fluids can resist motion through a yield stress. We identify two mechanisms that can prevent droplet detachment from its edge depending on the shear-dependence: shear thickening reopens due to generation of vorticity near the neck, whereas strong shear-thinning allows capillary pressure to reopen it due to curvature changes. Remarkably, this latter mechanism also arises in the Newtonian limit as the viscosity approaches zero, demonstrating that an almost inviscid filament need not undergo classical end pinching, contrary to the prevailing picture in the literature.

[Phys. Rev. Fluids 11, 073303] Published Thu Jul 30, 2026

In this work smectic bubbles with millimeter diameters, but only nanometer film thicknesses, are exposed in microgravity experiments to high electric fields to study field effects on film inclusions. The observed motion of islands and droplets in the film plane can be considered as a quasi-two-dimensional analogue of electrospraying. Different mobilities of anions and cations of the ionic dopants make the effect polarity dependent. The image shows the motion of islands (color coded blue to brown) when a high electric field at the anode (brown bar) is switched off at time $t=0$.

[Phys. Rev. Fluids 11, 073606] Published Thu Jul 30, 2026

Water injection is a promising technology for mitigating pollutant emissions from hydrogen combustion. However, the high reactivity and diffusivity of hydrogen flames make droplet–flame interactions particularly intricate. Using two-dimensional detailed-chemistry simulations, we show that a single droplet locally modifies the flame displacement speed and heat release rate, while altering flame stretch through droplet-induced curvature. We also propose a phenomenological model to predict the local flame displacement and velocity during the droplet-flame interaction.

[Phys. Rev. Fluids 11, 073201] Published Wed Jul 29, 2026

Why do clean spherical bubbles spread laterally even after they leave each other’s wakes? Experiments and reduced-order modeling reveal that bubble chains disperse through two successive mechanisms: wake-induced lift initiates lateral dispersion, while a bubble-induced upward flow drives the second stage. The findings reveal how pairwise wake interactions give rise to collective bubble dynamics.

[Phys. Rev. Fluids 11, 073604] Published Wed Jul 29, 2026

The sound produced by a detaching bubble is known to arise from its volumetric oscillations, but the factors driving the oscillation amplitude has remained an open question. We perform experiments using two bubble-generation methods, and observe that both the shape and amplitude of the pressure signal depend strongly on the bubble formation mechanisms. Using a large set of experimental data, we identify that the oscillation amplitude is mainly controlled by the initial growth velocity of the bubble. Furthermore, we propose a simple model that captures the onset of the acoustic signal as a consequence of the bubble pinch-off dynamics.

[Phys. Rev. Fluids 11, 073605] Published Wed Jul 29, 2026

We study collisions of small inertial particles suspended in a background flow. These particles may be inert plankton in the ocean or water droplets in clouds. Previous studies have shown that such collisions or caustics require particles to pass through regions of high strain in the flow. Our work finds that the type of strain is crucial, not just its magnitude. Regions of large compressive strain trigger caustics, whereas particles survive caustics despite encountering large strain if they come from extensional strain. Extending the study of caustics to finitely dense particles, we show that the level of strain required for caustics increases with decreasing particle density.

[Phys. Rev. Fluids 11, 074304] Published Wed Jul 29, 2026

We introduce a sequential approach to augment the shear stress transport-conditioned (SST-CND) model, which was originally trained on 2D flows, in 3D scenarios. 3D field inversion is first performed to obtain the distribution of the augmentation term. Then, features that are nonzero only in 3D scenarios are selected to build the expression using symbolic regression. The resultant SST-CND3D model preserves the original model’s capabilities in 2D flows, while showing significant improvement in 3D complex cases, including a real-world high-lift device.

[Phys. Rev. Fluids 11, 074607] Published Wed Jul 29, 2026

Acoustic liners are widely used for noise reduction in aero-engines, but the physical mechanisms governing their aerodynamic drag remain insufficiently documented. Based on pressure-drop measurements in a turbulent channel over a wide range of Reynolds numbers, this study identifies distinct drag regimes and reveals two markedly different behaviors within the transitional regime. In particular, large drag increases are shown to be associated with the onset of aeroacoustic resonance at the liner resonance frequency, while the relative importance of liner geometry is captured through a frontal-solidity-based parameter.

[Phys. Rev. Fluids 11, 074608] Published Wed Jul 29, 2026

[Phys. Rev. Fluids 11, 079901] Published Wed Jul 29, 2026

We embark on a 30-day journey following the flow of a high-viscosity liquid through a capillary tube to assess how existing theoretical models, which also account for the dynamic nature of the contact angle, perform in long-term imbibition processes. The journey reveals the persistent and diffusive nature of imbibition processes for liquids with extreme values of viscosity.

[Phys. Rev. Fluids 11, L072001] Published Wed Jul 29, 2026

A wind-turbine wake in a pressurized-air wind tunnel was forced via slow periodic oscillations in the turbine rotation rate. Flow measurements identified traveling waves in the wake, which could be controlled by independently varying the turbine thrust and tip-speed ratio. The results demonstrate the importance of advection for the modeling and control of wind-turbine wakes, even at nominally quasi-steady time scales.

[Phys. Rev. Fluids 11, 070501] Published Tue Jul 28, 2026

Shear-thinning is ubiquitous in biological and industrial fluids, yet its influence on the instability of time-periodic shear flows remains poorly understood. Using Floquet stability analysis of the Stokes layer in Carreau fluids, we show that shear-thinning can either suppress or promote instability depending on the characteristic fluid response time. The study further identifies a phase-dependent energy-transfer mechanism governing instability in a time-periodic shear flow, which has not been revealed in the literature, providing a dynamic counterpart to the classical energy-production mechanism in steady shear flows.

[Phys. Rev. Fluids 11, 073902] Published Tue Jul 28, 2026

Oscillatory flows in compliant channels are common to a number of soft-hydraulic problems, from physiological transport to microfluidics. Recently, elastoinertial rectification was shown to lead to streaming in these systems. We develop this theory for a two-dimensional (2D) channel with a confined, nearly incompressible elastic layer as its wall and validate the predictions against detailed Lagrangian–Eulerian fluid–structure interaction simulations. Surprisingly, the nearly incompressible 2D layer introduces new physics: resonance-like amplification of streaming at specific Womersley numbers. Our results offer design principles for optimizing flow rectification in soft microsystems.

[Phys. Rev. Fluids 11, 074102] Published Tue Jul 28, 2026

A previously undocumented Reynolds-number-dependent transition is identified in the wake of a rounded-edge slanted afterbody, from a centerline-separated to a novel centerline-attached vortex state. The transition produces a pronounced drag reduction through the collapse of the centerline recirculation region as the upstream boundary layer becomes turbulent. These findings explore experimental evidence linking laminar separation bubble dynamics, shear-layer instability, and wake-state transitions in this canonical bluff-body geometry.

[Phys. Rev. Fluids 11, 074702] Published Tue Jul 28, 2026

The comprehensive statistics of a turbulent flow field can in principle be captured by Hopf’s functional approach; however, the resulting functional equations have remained largely intractable. We here study a simplified passive vector model, whose Hopf equation is solved exactly by an ensemble of Gaussian fields. Based on both theory and simulations, we find that the model displays a fluctuating energy flux from large to small scales. The resulting intermittency at the small scales can be understood as arising from a probabilistic mixture of Gaussian sub-ensembles.

[Phys. Rev. Fluids 11, 074606] Published Thu Jul 23, 2026

Put a soap bubble in an electric field and it stretches into a taller, smooth dome. Turn the field up and, past a critical point, the top sharpens into a pointed cone that fires off a thin jet. Imaging the bubble from the side, we follow this whole sequence in one experiment and find two things. Bubbles of different sizes deform along the same curve once the field is rescaled by bubble size and surface tension, so one balance between electric and capillary forces sets the shape. And the cone is far sharper than Taylor’s classic value, because it is selected while the film is still rushing toward the jet rather than resting in equilibrium.

[Phys. Rev. Fluids 11, 074003] Published Wed Jul 22, 2026

Droplet mixing is vital in many practical applications, yet the underlying physical mechanisms remain poorly understood. This work uses carefully validated numerical simulations to investigate the mixing dynamics of inkjet printed droplets. Our results show that impact-driven flows contribute only weakly to mixing, while molecular diffusion governs homogenization over a timescale of seconds. We perform studies to understand how droplet size, spacing, volume ratio, and substrate wettability influence mixing, producing methods to estimate mixing times for droplet-based manufacturing processes.

[Phys. Rev. Fluids 11, 073603] Published Tue Jul 21, 2026

Rotating bluff bodies are widely used to control wake instabilities and fluid forces, but the role of wake–body interactions in multi-body configurations remains less understood. Direct simulations of isolated and tandem transversely rotating spheres show that rotation can suppress classical shedding and reorganize the wake into double-threaded vortical structures. However, tandem interactions can overturn this stabilizing effect, sustaining unsteady wakes and strongly modulating drag and lift.

[Phys. Rev. Fluids 11, 074101] Published Tue Jul 21, 2026

High-fidelity simulations have become indispensable for uncovering the physics of turbulent two-phase flows, yet quantitative guidelines for the grid and time-step requirements needed to accurately resolve interface dynamics have been lacking. We derive scaling laws that predict these computational requirements as functions of Reynolds, Weber, and Capillary numbers; identify distinct inertia- and viscous-dominated regimes; and introduce a new dimensionless parameter that unifies their classification. The resulting framework provides practical $a$ $priori$ resolution criteria and computational cost estimates for predictive interface-resolved simulations.

[Phys. Rev. Fluids 11, 074303] Published Mon Jul 20, 2026

Invariants, such as energy or enstrophy, are central to turbulence theory. Some systems behave in a sub-space between two well-known limits where invariants are known. Here, we demonstrate that invariants can also be defined for these intermediate cases. Knowledge of the invariants enables the development of simple models for the multiscale dynamics of such systems.

[Phys. Rev. Fluids 11, 074605] Published Fri Jul 17, 2026

Using direct numerical simulations of incompressible turbulence at Taylor-scale Reynolds numbers $R_{\lambda }$ up to about 1740, we examine spectra, two-point correlations, and second-order local-average moments of the energy dissipation rate ϵ and enstrophy Ω. Correlations and local-average moments exhibit larger scaling exponents for fluctuating fields than for total fields over nearby but distinct ranges. In both statistics, squared-mean contributions are nonnegligible relative to fluctuating contributions. Thus, total- and fluctuation-field exponents need not coincide over these ranges. Results suggest $R_{\lambda }$ ≈ 1740 remains insufficient to reach the asymptotic regime assumed in intermittency theories.

[Phys. Rev. Fluids 11, 074603] Published Thu Jul 16, 2026

Data assimilation and symbolic regression are used to formulate an analytical correction to the Spalart-Allmaras model, addressing local deficiencies in its production term. The correction improves separated-flow predictions while preserving the performance of the baseline model for wall-attached flows. Tests on multiple two-dimensional flow cases confirm the applicability of the correction across diverse configurations.

[Phys. Rev. Fluids 11, 074604] Published Thu Jul 16, 2026

Dense non-Brownian suspensions undergo a rheological transition with increasing shear rate, from a Newtonian scaling where stress grows linearly, to a Bagnoldian scaling where it grows quadratically. For suspensions devoid of frictional contacts due to electrostatic repulsive forces keeping the particles apart, our discrete element simulations reveal the shear rate marking the onset of the inertial regime to exhibit a critical behavior as the suspension approaches jamming. Our results show this criticality to be tied to a diverging microstructural length scale, larger than any individual particle, that governs the emergence of inertial effects within the suspension.

[Phys. Rev. Fluids 11, 074302] Published Wed Jul 15, 2026

Using qualitative flow diagnostics and quantitative pressure measurements, this study investigates hypersonic flow over a cone-mounted axisymmetric cavity to assess the influence of Reynolds number, aspect ratio, and excess rear-face height. A distinct mode-shifting behavior from flapping-dominated to Kelvin-Helmholtz-dominated oscillations is identified at the highest aspect ratio, owing to a possible turbulent transition of the shear layer with a change in Reynolds number, which is found to be absent in the two-dimensional cavity configuration. The excess rear-face-height cases also demonstrate the ability to alter the dominant instability mechanism and resonance characteristics.

[Phys. Rev. Fluids 11, 073401] Published Tue Jul 14, 2026

Electrophoresis is often used in combination with external flows for enhanced particle separation. However, the resulting motion when particles have nonuniform surface charge remains poorly understood. This dynamic problem is solved here using an efficient and exact reduced order model. It reveals the diverse set of trajectories emerging from the coupling between the particle’s rotation and its uneven surface charge with potential applications in medical diagnosis and analytical chemistry.

[Phys. Rev. Fluids 11, 073702] Published Tue Jul 14, 2026

Low Reynolds number airfoils may stall abruptly due to laminar separation bubble bursting. Periodic boundary layer forcing can promote transition through the excitation of natural instabilities, and thereby delay or prevent stall. In this study, forcing is provided by a plasma actuator and the influence of varying forcing amplitude on the bursting transient is examined using particle-image velocimetry and surface pressure measurements. Increasing the forcing amplitude delays and increases the variance in the bursting start time. However, the dynamics of the bursting process are largely insensitive to forcing amplitude. For higher forcing amplitudes, bursting is entirely prevented.

[Phys. Rev. Fluids 11, 073901] Published Tue Jul 14, 2026

In multiphase turbulent flows, kinetic and interfacial energies usually coexist in a subtle balance, but their mutual conversion often goes unnoticed in statistically steady regimes. Our work introduces a controlled, time-periodic forcing to break this steadiness, thereby revealing the dynamic cycle of energy injection, conversion, and dissipation. By extending the $k-ϵ$ model to include surface energy and nonequilibrium effects, and by linearizing the system, we uncover the intricate time scales that govern the coupling between these processes.

[Phys. Rev. Fluids 11, 074002] Published Tue Jul 14, 2026

The pinch-off of drops and bubbles from a needle are classic examples of hydrodynamic singularities, in which a fluid body splits into two. While even small amounts of polymers strongly delay drop breakup by forming long liquid threads, recent experiments show that bubble pinch-off remains largely unaffected. In this article we demonstrate that polymer stretching cannot compete with the violent inertial collapse governing bubble pinch-off. Only for sufficiently high polymer concentrations and small needle sizes can viscoelastic effects delay breakup, resulting in the formation of air cavities.

[Phys. Rev. Fluids 11, 073302] Published Mon Jul 13, 2026

We experimentally and numerically investigate nanosecond laser-induced jetting dynamics of a free-falling micro-sized liquid tin droplet. Following laser impact, the droplet rapidly expands and retracts, leading to the formation of a high-speed axial jet. A specific combination of laser-induced pressure and its angular distribution on the droplet surface drives cavity formation, ultimately giving rise to a singular jet. We reveal the underlying mechanism and construct a phase diagram explaining jet emergence as the result of a subtle interplay between droplet curvature during retraction and radial flow.

[Phys. Rev. Fluids 11, 073602] Published Mon Jul 13, 2026

Charge transfer between particles is believed to strongly influence the mechanical properties of many suspensions, yet it remains difficult to observe directly. We demonstrate that biopolymer microcapsules exhibit a unique bouncing dynamics under an alternating electric field that is consistent with repeated charge transfer during contact. These findings identify Coulombic interactions as the origin of the attractive forces responsible for the fragile gel behavior and yield stress previously observed in suspensions of these microcapsules.

[Phys. Rev. Fluids 11, 073701] Published Mon Jul 13, 2026

Controlling the distribution of colloidal particles during drying of a thin porous medium is of importance for various technological applications. The liquid phase distribution during drying in a thin system is strongly affected by two effects, referred to as the edge and breakthrough effects. The impact on the colloid distribution during drying of both effects is studied. Simulations indicate markedly more uniform colloid spatial distributions as the result of both effects compared to predictions based on the standard model ignoring these effects.

[Phys. Rev. Fluids 11, 074301] Published Mon Jul 13, 2026

Particle-vortex interactions in quantum turbulence are essential for interpreting the results from particle-laden experiments in superfluid He II thermal counterflow. In this experimental investigation, we extracted and analyzed trapping and de-trapping processes of small particles on quantum vortex lines. Our results show an asymmetry between the two processes, indicating that they are governed by distinct physical mechanisms, and suggest that they exhibit self-similar features across small time lags. These results deepen our understanding of trapping and de-trapping processes of particles, and the dynamics of particle motion in turbulent thermal counterflow under two-fluid interactions.

[Phys. Rev. Fluids 11, 074602] Published Mon Jul 13, 2026

Experimental studies of fluid–structure interactions (FSI) rarely capture dense, simultaneous measurements of both the fluid and solid phases, which limits analysis of the coupled dynamics. We present a physics-informed data assimilation framework that reconstructs both the flow and structure from sparse, off-body particle tracks, i.e., without requiring a constitutive model or direct observations of the structure. The method accurately recovers coupled dynamics in 2D and 3D benchmarks, allowing for quantitative measurements of FSI from limited data.

[Phys. Rev. Fluids 11, 074901] Published Mon Jul 13, 2026

Ordered vortex lattices, familiar from quantum systems like Bose-Einstein condensates and type II superconductors, have emerged in classical rotating turbulence, but the mechanisms controlling their stability remain elusive. By embedding ideal, defect-free triangular arrays into three-dimensional turbulent flows, we map the region of parameter space where these structures survive and establish their characteristics. Their lifetimes obey a memoryless random process whose mean depends sensitively on the Rossby number and energetic balance, with optimally tuned dissipation yielding long-lived states whose statistics resemble those of critical systems.

[Phys. Rev. Fluids 11, 074401] Published Fri Jul 10, 2026

The intense fluctuations of the rate of energy dissipation, an essential aspect of intermittency, are of constant interest in turbulence research. Measuring the energy dissipation, however, is extremely challenging: Most of our knowledge comes from hot-wire measurements of the derivative of the streamwise velocity component, which is generally regarded as a surrogate of the energy dissipation. Here we show that the moments of the energy dissipation cannot reduce to those of its surrogate, as a consequence of a fundamental property of the rate of strain tensor in turbulence. However, the predictions based on assuming a simplified strain rate tensor are accurate to within a few percent.

[Phys. Rev. Fluids 11, 074601] Published Fri Jul 10, 2026

We show that the interaction of a vortex pair with a localized polymeric fluid layer can generate secondary and tertiary vortices through polymer stress gradients. Numerical simulations reveal that elastic stresses significantly modify vorticity production and energy transfer, leading to flow behaviors not observed in Newtonian fluids. The image shows the vorticity field during the interaction.

[Phys. Rev. Fluids 11, 073301] Published Mon Jul 06, 2026

We characterize the nonlinear pressure drop–flow rate relation of elongated bubble trains in capillary tubes by incorporating thin-film hydrodynamics at low capillary numbers. We show that pore-scale statistical heterogeneity in capillary bundles induces systematic deviations from the single-phase limit, controlled by both the pore-size distribution and flow parameters. We identify a crossover between sublinear regimes with exponents ranging from 2/3 to 1, connecting the Bretherton and Darcy limits and in qualitative agreement with values reported for immiscible two-phase flow in porous media.

[Phys. Rev. Fluids 11, 073601] Published Mon Jul 06, 2026

We revisit the classical homogeneous shear assumption in cone-and-plate rheometry over a slip boundary condition, and resolve inconsistencies between two slip boundary formulations. Our results show that a fixed slip-length model induces radial shear-rate non-uniformity, whereas a constant wall-stress formulation restores homogeneous shear via a radius-dependent slip length. Extending our work to shear-thinning Carreau fluids, we demonstrate a strong shear-rate dependence of drag reduction and effective slip length. Despite distinct local flow structures, both models yield consistent area-averaged slip from torque measurements, providing a unified framework for slip quantification.

[Phys. Rev. Fluids 11, 074001] Published Mon Jul 06, 2026

Unsteady thin-airfoil theory is a straightforward reduced-order framework for arbitrary airfoil motions and geometries. However, an inconsistency appears when recovering classical unsteady problems: Glauert’s bound-vorticity expansion is not uniformly convergent at the trailing edge in unsteady motion. Revisiting Wagner’s problem through the unsteady Kutta condition, this work derives a recurrence for the bound-vorticity coefficients and builds a uniformly convergent bound vortex-sheet formulation with a discrete-vortex equivalent. With few terms, the method ensures bound-wake continuity, zero trailing-edge loading, and smooth transient predictions for Wagner’s indicial problem

[Phys. Rev. Fluids 11, 074701] Published Mon Jul 06, 2026

Turbulent thermal convection often organizes into large-scale flow structures that control heat and momentum transport, yet their dynamics in very wide systems remain largely unexplored. Using a liquid-metal Rayleigh–Bénard convection experiment with an extreme aspect ratio of 25, we demonstrate that jump rope vortex dynamics persist even within turbulent convective superstructures. The observed oscillatory behavior follows the same scaling laws previously identified in much smaller systems, indicating that jump rope vortex dynamics are not confined to specific geometries but remain relevant even in spatially extended convection at extreme aspect ratios.

[Phys. Rev. Fluids 11, 063503] Published Tue Jun 30, 2026

Active grids are widely used to generate turbulence, yet their near-grid region remains poorly understood. We show that global blockage is a key parameter governing near-grid turbulence statistics, driving qualitatively different behavior when grid configuration changes, in contrast to trends observed further downstream. We further reveal that forcing signatures persist strongly at large scales but decay toward dissipative scales, marking a transition from forcing-dominated to more universal turbulence.

[Phys. Rev. Fluids 11, 064617] Published Tue Jun 30, 2026