Latest papers in fluid mechanics

Author(s): Dušan Božić, Anubhav Dwivedi, and Mihailo R. Jovanović

Subcritical transition in shear flows arise from the interplay between linear non-modal amplification and nonlinear interactions, yet their quantitative connection remains unresolved. We bridge this gap by deriving a framework from the Navier–Stokes equations, in which a forcing-amplitude expansion links oblique disturbances to finite-amplitude streaks consistent with direct numerical simulations. This hierarchy shows that the same resolvent structure governing linear amplification organizes the dynamics at all orders in the perturbation series. Breakdown of this series marks the onset of secondary instability, providing a quantitative bridge between non-modal growth and classical transition theory.

[Phys. Rev. Fluids 11, 063901] Published Thu Jun 04, 2026

Author(s): Fabio Guglietta, Martino Andrea Scarpolini, Francesco Viola, and Luca Biferale

Blood flow in the human heart is far from a smooth stream: it is a rapidly changing, intermittent motion shaped by moving walls, valves, and pulsatile forcing. By following Lagrangian tracers through a patient-specific simulation of the left heart, this study reveals where and when turbulent fluctuations become most intense. The results show that Lagrangian statistics can expose chamber-specific flow signatures and detect the enhanced intermittency produced by a stiffened aortic valve, opening a route toward sharper assessment of pathological cardiac flows.

[Phys. Rev. Fluids 11, 064604] Published Thu Jun 04, 2026

Author(s): Antoine Parrenin, Cees van Rijn, and Daniel Bonn

The characteristic fanning out of spray clouds, whether spraying perfume or spray painting, is familiar. We studied spray cloud formation for parallel jet nozzles as a function of the pressure of the surrounding air. Our microfabricated nozzles with parallel 4μm holes produce multiple microjets; we find that these form conical spray clouds via air friction through a Kelvin-Helmholtz instability. As a consequence, if the air pressure is lowered in the transparent vacuum chamber in which we perform our experiments, the spray cloud disappears altogether. As shown in the figure, below a critical air pressure characteristic of the instability, the jets then simply propagate in straight lines.

[Phys. Rev. Fluids 11, L062301] Published Thu Jun 04, 2026

Author(s): Daisuke Noto and Hugo N. Ulloa

The Oberbeck–Boussinesq (OB) approximation underpins much of our understanding of thermally driven flows, yet its validity in coldwater systems remains largely unexplored. Using numerical simulations of ice-bounded horizontal and vertical convection, we show that temperature-dependent material properties significantly modify flow structures and global transport, even where density variations are weak. In some cases, they induce anomalous reversals between warm and cold circulations, leading to O(10%) errors in predicted heat fluxes and ice melt rates, highlighting the non-negligible role of thermophysical variability in cryospheric waters.

[Phys. Rev. Fluids 11, 063501] Published Wed Jun 03, 2026

Author(s): Paolo Botticini, Davide Picchi, and Pietro Poesio

Elongated bubbles in microchannels offer a promising yet still poorly quantified route to enhance convective heat transfer. We develop a one-dimensional model capturing the interplay between advection, diffusion, viscous dissipation, and wall heat flux in the thin film around the bubble. The results reveal scaling laws for the Nusselt number, linking thin-film flow dynamics directly to heat transfer efficiency.

[Phys. Rev. Fluids 11, 063602] Published Wed Jun 03, 2026

Author(s): Haozhe Geng, Wen-Li Chen, Hui Li, and Donglai Gao

Granular flows interacting with obstacles are central to geophysical hazard mitigation, yet the post-impact evolution on horizontal run-out zones remains underexplored. This experimental study reveals a converging granular front formed downstream of a single cylinder along with volume‑dependent regime transitions from shock‑induced bifurcation to rapid stabilization. Scaling laws for front velocity, run up height, and centroid displacement demonstrate that initial column geometry and basal friction dominate over obstacle size and particle diameter. These findings decouple local flow perturbations from bulk deposition, providing predictive insights for designing barriers in confined terrains.

[Phys. Rev. Fluids 11, 063801] Published Wed Jun 03, 2026

Author(s): Subhajyoti Sahoo and Ameeya Kumar Nayak

Electroosmotic transport in soft microchannels is often modeled when more often the channel geometry was fixed, but the wall deformation and surface forces strongly influence the flow in confined gaps. A nonlinear lubrication framework is developed for a constricted compliant microchannel, coupling with the Helmholtz–Smoluchowski slip, electric-field focusing, Kirchhoff–Love wall bending, and DLVO disjoining pressure. It is identified that the stiff-wall, compliance-limited, and small-gap saturation regimes provided the scaling laws which relates the throughput analysis and deformation to curvature, wall stiffness, surface conduction, and intermolecular forces.

[Phys. Rev. Fluids 11, 064201] Published Tue Jun 02, 2026

Author(s): Kyo Yoshida

An ensemble model of turbulence based on states with constant flux in wavenumber space was proposed in [K. Yoshida, Phys. Rev. E 106, 045106 (2022)]. The justification of this ensemble model relies on the conjecture that almost all states with constant flux correspond to turbulence states. To verify…

[Phys. Rev. E 113, 065101] Published Mon Jun 01, 2026

Author(s): Sunand Bhattacharjee, Sangtae Kim, and Vivek Narsimhan

Ferrofluid droplets deform under the competing action of flow, surface tension, and magnetic stresses, making ferrofluid emulsions promising magnetically tunable complex fluids. We develop an analytical small-deformation theory for droplets in general linear flows and uniform magnetic fields. The theory captures the coupling between flow and field, predicting shape evolution, droplet breakup, and the rheology of dilute emulsions.

[Phys. Rev. Fluids 11, 063601] Published Mon Jun 01, 2026

Author(s): Aliénor Rivière, David Fabre, Jacques Magnaudet, and François Gallaire

We study the linear dynamics of an incompressible gas bubble in a biaxial straining flow, characterized by two stretching and one compressing directions, in the presence of finite inertial effects. The system undergoes a saddle-node bifurcation and exhibits strongly different equilibrium shapes when varying the Ohnesorge number comparing viscous and capillary effects. Linear stability analysis reveals the rich dynamics of the system. Bubbles are found to be significantly more stable in biaxial than in uniaxial flows, which may explain why turbulent breakup mainly occurs in uniaxial regions despite biaxial regions being more common.

[Phys. Rev. Fluids 11, 064001] Published Mon Jun 01, 2026

Author(s): Ajay Jangid and Manoranjan Mishra

This study investigates how nonlinear Langmuir adsorption modifies the transport, deformation, and viscous fingering dynamics of a finite miscible solute blob in porous media using a high-resolution Fourier pseudospectral method. The solute’s upstream advection speed decreases with increasing adsorption nonlinearity. The results show that adsorption can suppress or reintroduce viscous fingering, producing lump, comet, and fingered morphologies. Mixing exhibits nonmonotonic behavior at moderate viscosity contrasts, but increases monotonically for larger viscosity contrasts.

[Phys. Rev. Fluids 11, 064002] Published Mon Jun 01, 2026

Author(s): L. Rotily and E. Villermaux

The evaporation dynamics of a stretched spray lamellae is a paradigm for dense sprays evaporation. We consider lamellae made of densely packed micron-sized droplets of liquids with different volatilities, initially in equilibrium with their vapor. We confirm that the lifetime of an individual droplet is much larger than expected from the usual d-squared law for isolated droplets evaporating in a quiescent environment. By analogy with mixing times of scalars, we show that the boundary between the spray and the diluting environment is controlled by the dynamics of its saturating vapor concentration field, explaining the substantial evaporation delay despite the liquid’s division into fine droplets.

[Phys. Rev. Fluids 11, 064501] Published Mon Jun 01, 2026

Author(s): Lukas A. Codispoti, Daniel W. Meyer, and Patrick Jenny

Turbulence accelerates droplet growth in warm clouds, but reliable collision-kernel models remain elusive; and the effect of polydispersity beyond gravitational settling is often not accounted for. We provide a comprehensive map of the bidisperse collision kernel across St ∈ [002_2] and demonstrate that current models systematically overpredict cross-species clustering. We propose a compact parameterization that captures polydisperse collisions across Reynolds numbers, and show that droplet growth is markedly accelerated in highly dissipative parcels—supporting turbulent intermittency as a viable pathway past the warm-rain bottleneck.

[Phys. Rev. Fluids 11, 064601] Published Mon Jun 01, 2026

Author(s): Wilson Lu, Leon Chan, and Andrew Ooi

Despite its geometric symmetry, flow past a highly confined cylinder is known to develop an asymmetric wake. This motivates an examination of the conditions under which this asymmetry is lost. The present results indicate that upstream turbulence can suppress wake bias and restore global symmetry. Turbulence induces early breakdown of the cylinder shear layers immediately after separation, disrupting their coupling with the wall shear layers that would otherwise sustain the asymmetric wake. These results further suggest that any mechanism capable of triggering early breakdown of the cylinder shear layers may likewise promote recovery of global symmetry.

[Phys. Rev. Fluids 11, 064602] Published Mon Jun 01, 2026

Author(s): Ben Steinfurth, Lukas Fuchs, Carolina Cura, Jakob G. R. von Saldern, Kilian Oberleithner, and Julien Weiss

Turbulent separation bubbles are known to exhibit low-frequency “breathing” but its origin remains unclear. This work shows that the dominant long-time dynamics can be captured by a nonlinear Langevin model fitted to Proper Orthogonal Decomposition amplitudes from time-resolved Particle Image Velocimetry. The results reveal bimodal, noise-driven switching between preferred separation states, providing a probabilistic dynamical-systems interpretation of the low-frequency unsteadiness.

[Phys. Rev. Fluids 11, 064603] Published Mon Jun 01, 2026

Author(s): Ahmed Sherif, Jesse Etan Smith, and Leif Ristroph

Light and sound waves can be beamed at molecules or particulates to exert forces, induce motion, and control position. New experiments show that water waves can be used in much the same way at larger scales, and the findings open up new opportunities for action-at-a-distance manipulation. By controlling the shapes of suspended structures, the article shows that they may even be moved sideways or perpendicular to incoming waves. Further, by controlling the form of the wave field, objects can be stably held in place or “tweezed” at a desired location.

[Phys. Rev. Fluids 11, 064801] Published Mon Jun 01, 2026

Author(s): Satoshi Matsumoto, Masanobu Inubushi, and Susumu Goto

We identify the essential role of temporal filtering in enabling data-driven closure models that reproduce turbulent dynamics in the energy-containing range. The scope of the present study differs fundamentally from conventional subgrid-scale modeling, which relies on the universality of small-scale dynamics. While the model constructed on training data preprocessed with a temporal low-pass filter stably and accurately captures the chaotic dynamics of the largest eddies in turbulence, the one trained without temporal low-pass filtering exhibits steady or periodic behavior and fails to capture the chaotic dynamics of the energy-containing range.

[Phys. Rev. Fluids 11, 054606] Published Thu May 28, 2026

Author(s): Daniel Abdulah, Wanying Kang, and Jeremy Rekier

Inertia–gravity waves generated by tidal flow over topography transfer energy and momentum, shaping ocean and atmospheric dynamics. We derive a general solution including non-traditional Coriolis effects, finite depth effects, and non-hydrostatic terms. Non-traditional effects broaden where waves can exist and enhance conversion, especially at low latitudes and given weak stratification. These results expand predictions for dynamics on icy sattelites and other planetary applications.

[Phys. Rev. Fluids 11, 053802] Published Wed May 27, 2026

Author(s): Daniel Abdulah and Wanying Kang

Inertia–gravity waves generated by flow over topography transfer energy and momentum between the ocean and its boundaries. Finite depth forces the wave to be a sum of vertical modes, and when the gravest mode has a length scale comparable to the topographic source, wave conversion and drag are suppressed. We show how a relaxation of the hydrostatic approximation and acoustic approximation influence this suppression.

[Phys. Rev. Fluids 11, 054804] Published Wed May 27, 2026

Author(s): Bal Krishan, Preetika Rastogi, D. Chaitanya Kumar Rao, Niket S. Kaisare, Madivala G. Basavaraj, and Saptarshi Basu

Efficient atomization of multicomponent fuel droplets is central to cleaner and more efficient combustion technologies. This study investigates the bubble-driven breakup of acoustically levitated microemulsion droplets under laser heating, revealing alternative pathways to atomization in stable, practically relevant emulsion fuels. Using high-speed imaging, distinct fragmentation modes are identified that are governed by heating intensity, bubble growth dynamics, and hydrodynamic instabilities, including Faraday and Rayleigh–Taylor mechanisms. The findings provide new physical insight into atomization processes relevant to cleaner combustion and advanced spray technologies.

[Phys. Rev. Fluids 11, 053605] Published Tue May 26, 2026