New Papers in Fluid Mechanics

Author(s): Yifan Ma, Chenren Chen, and Zhigang Zhai

This work develops a linear model under a “total transmission” condition that isolates adjacent and cross-interface couplings in a three-interface system by suppressing reverberating waves. We then demonstrate bidirectional modulation of interface evolution by layer spacing and initial amplitude, showing that coupling can either stabilize or destabilize interfaces. Finally, we analytically derive “freeze-out” criteria for single-interface stagnation via parameter tuning and validate it numerically. These results advance multilayer Richtmyer-Meshkov instability physics, provide control strategies for shock-accelerated mixing in inertial confinement fusion, and impact reflected-wave studies.

[Phys. Rev. Fluids 11, 063902] Published Thu Jun 25, 2026

Author(s): Tachin Ruangkriengsin, Günther Turk, and Howard A. Stone

Resolving the near-wall motion of self-diffusiophoretic Janus particles is numerically challenging because of the steep solute concentration gradients within the narrow gap. We develop an asymptotic theory in the distinguished limit where the inert face is comparable in size to the lubrication region. For axisymmetric and slightly tilted configurations, we obtain explicit particle velocities and gap concentration fields that reveal how cap size influences the particle’s rotational stability near the wall.

[Phys. Rev. Fluids 11, 064103] Published Wed Jun 24, 2026

Author(s): Shilin Yu, Wenbao Zheng, Chao Zeng, and Wen Deng

The oscillatory dynamics of trapped nonwetting fluids in pore constrictions influence multiphase flow and transient fluid mobility in geologic media. Although the small-amplitude linear response is relatively well understood, the mechanism responsible for nonlinear behavior at finite-amplitudes rema…

[Phys. Rev. E 113, 065109] Published Tue Jun 23, 2026

Author(s): Mrinal Jyoti Powdel and Samriddhi Sankar Ray

We show that the spread of infinitesimal perturbations in a turbulent density-stratified fluid becomes slower with increasing degree of stratification. With a higher degree of stratification, the spatial growth of the uncertainty gets more and more compressed along the direction of stratification. Despite this, the temporal growth of perturbations follows the same universal behavior: an initial decay followed by an exponential growth, ultimately leading to saturation. The rate of growth of the perturbation, however, gets affected by stratification through the strain-mediated dynamics of the underlying velocity field, rather than through direct coupling with the density fluctuations.

[Phys. Rev. Fluids 11, 064615] Published Tue Jun 23, 2026

Author(s): Boqian Yan and Xiaoyu Tang

While droplet impact on liquid pools is well studied for Newtonian fluids, particle suspensions introduce complex non-Newtonian dynamics. This work experimentally identifies five distinct impact regimes for cornstarch suspension droplets, revealing unique phenomena like “wrapped bubbles” and impact-induced jamming that are absent in simple fluids. Through an energy balance analysis, the authors demonstrate that these behaviors are dictated by a direct competition between pool cavity dynamics and suspension rheology. The resulting transition boundaries offer practical guidance for engineering applications like 3D printing.

[Phys. Rev. Fluids 11, 060501] Published Mon Jun 22, 2026

Author(s): Zhenyu Yuan (袁震宇) and Chang Shu (舒昌)

We propose a moment gas kinetic flux solver (MGKFS). Like conventional GKFS, the governing equations for mass, momentum, and energy are still solved by the finite volume method (FVM). In addition, a set of evolution equations for stresses and heat fluxes are also solved by FVM, in which numerical fluxes are evaluated by high-order moments of the distribution function at cell interfaces. That is, high-order moment equations are directly computed via moment integration of a reconstructed gas distribution function at cell interfaces. This strategy not only provides a new closure method for the 13-moment system, but also avoids tedious boundary conditions for stress and heat flux equations.

[Phys. Rev. Fluids 11, 063401] Published Mon Jun 22, 2026

Author(s): Tianpei Cheng, Haijian Yang, Mei Zhang, and Ke Xu

Rayleigh–Darcy convection (RDC) in porous media controls mass and heat transfer in many geological systems. We show that permeability heterogeneity fundamentally reshapes RDC. The permeability correlation length interacts with intrinsic flow-structure scales that determine the convection pattern. High-resolution simulations reveal three distinct heterogeneity regimes depending on Rayleigh number (Ra): (i) At low Ra stable convection cells are constrained; (ii) At intermediate Ra microplume-driven transport is enhanced; and (iii) At high Ra heterogeneity becomes negligible or boundary-layer-controlled. This provides theoretical support for predicting convective mixing and scalar transport.

[Phys. Rev. Fluids 11, 063502] Published Mon Jun 22, 2026

Author(s): Sohyeun Kang, Jaejun Kim, Minseop Lee, and Daegyoum Kim

We experimentally investigate the detachment of a bubble injected from an orifice on a horizontally moving plate. By performing theoretical analysis based on force balance without empirical constants, we introduce a dimensionless parameter Rc that characterizes a transition between vertical buoyancy-dominated “rise” and horizontal shear-dominated “lift-off” regimes. Rc successfully captures the trends of both the bubble radius and inclination angle at detachment across all experimental conditions, and Rc = 0.8 indicates the transition boundary between the two regimes.

[Phys. Rev. Fluids 11, 063604] Published Mon Jun 22, 2026

Author(s): Fubao Yang, Yuhong Zhou, Peng Jin, Jinrong Liu, Zhixin Li, Lili Zhang, Gaole Dai, Liujun Xu, and Jiping Huang

Hydrodynamic metamaterials can steer liquids without disturbing surrounding flow, but passive designs have largely been limited to fixed environments and regular geometries. We show that extreme effective viscosity anisotropy, realized through simple microchannel height modulation and solid barriers in Hele-Shaw flows, decouples a metashell’s performance from the background viscosity. The resulting free-form metadevice remains invisible under environmental changes while accelerating flow in its core, as verified by simulations and experiments, opening a route to robust microfluidic control.

[Phys. Rev. Fluids 11, 064101] Published Mon Jun 22, 2026

Author(s): Kui Liu, An-Kang Gao, and Xi-Yun Lu

This study investigates a novel fluid–flexible filament system in which the filament is allowed to move laterally in a uniform flow. Once symmetry breaking occurs, the filament exhibits spontaneous and sustained translation, effectively self-propelling by extracting energy from the flow. The dynamics are governed primarily by the effective Reynolds number and effective bending stiffness. A reduced-order parameterized model is further developed to predict the filament’s equilibrium configuration and curvature.

[Phys. Rev. Fluids 11, 064102] Published Mon Jun 22, 2026

Author(s): Yi Cai, Jiachen Zhao, Runze Sun, Zhongzheng Wang, Emilie Sauret, and Yixing Gou

Electric field–driven droplet generation provides an active strategy for overcoming the limited controllability of conventional passive microfluidic methods; however, the mechanisms governing mode transitions under different combinations of electrical properties remain unclear. Here, we develop a coupled lattice Boltzmann–finite difference numerical framework to investigate electrohydrodynamic droplet formation in T-shaped microchannels under varying electric field strengths, permittivity ratios and conductivity ratios. We identify four droplet generation modes and reveal their transition mechanisms by analyzing interfacial charge distributions and electric-field forces.

[Phys. Rev. Fluids 11, 064202] Published Mon Jun 22, 2026

Author(s): Shakyajit Paik, Somnath Bhattacharyya, and Subrata Majhi

This study investigates the diffusiophoresis of charged rigid colloids in yield-stress viscoplastic fluids using fully coupled electrokinetic simulations supplemented by thin-double-layer analysis, and demonstrates new avenues for manipulating particles in complex viscoplastic media. The results show that shear-thinning rheology enhances particle velocity significantly, whereas yield stress suppresses particle mobility and can even induce stalling. In shear-thinning fluids, a reversal of diffusiophoretic motion is observed at lower values of the flow consistency index, which is suppressed when diffusion-dominated transport is amplified for multivalent electrolytes or at higher yield stresses.

[Phys. Rev. Fluids 11, 064203] Published Mon Jun 22, 2026

Author(s): L. Sundberg, F. Candelier, N. Fintzi, G. Voth, J. L. Pierson, K. Gustavsson, and B. Mehlig

Particle-shape symmetry determines the form of inertial hydrodynamic forces and torques acting on particles settling in a quiescent fluid. Exploiting these symmetries provides a systematic way of analyzing how particle shape influences unsteady settling dynamics, by classifying particles according to their shape-symmetry groups. Our results help to understand the connection between particle geometry and the transient dynamics observed in settling experiments with particles of different shapes.

[Phys. Rev. Fluids 11, 064305] Published Mon Jun 22, 2026

Author(s): Fanshuo Ma, Stéphanie Deboeuf, Pierre-Yves Lagrée, and Lydie Staron

We propose a continuum two-dimensional model for cohesive granular flows down inclines. Using the Contact Dynamics method, we explore the parameter space of inclination angle and adhesion strength for which steady uniform flows develop. We then compare free-surface velocity and plug thickness with the model. We find that, at moderate inertial numbers I, the flow rheology can be described by a linear μ(I) friction law supplemented by a macroscopic cohesive stress. The independence of friction and adhesion is confirmed within the investigated parameter range, and the macroscopic cohesive stress is found to scale linearly with local contact adhesion, in agreement with Rumpf’s prediction.

[Phys. Rev. Fluids 11, 064306] Published Mon Jun 22, 2026

Author(s): Brandon Yeung and Oliver T. Schmidt

We outline a workflow for examining statistically transient fluid flows, which eludes most standard modal analysis techniques. As a challenging example, we investigate the transient dynamics of a turbulent supersonic twin-rectangular jet flow. Forcing-induced perturbations are extracted using synchronized large-eddy simulations (LES) of the natural and forced jets, and a database is collected that captures an ensemble of realizations of these perturbations. From this ensemble, we study the time-varying mean flow deformation and perform space–time proper orthogonal decompositions.

[Phys. Rev. Fluids 11, 064614] Published Mon Jun 22, 2026

Author(s): Fanrong Xue, Shufan Zou, Ming Zhao, and Wei Liu

[Phys. Rev. Fluids 11, 069902] Published Mon Jun 22, 2026

Author(s): Tasawar Iqbal, Catherine Penington, Christian Thomas, and Lyndon Koens

Choanoflagellates, key marine microscopic filter feeders, display large diversity in their filter geometry. Comparing a simplified infinite cylindrical model for the filter with biological, we find that many choanoflagellate species exist near a ridge in the effective flux into the filter but away from a similar ridge in the power. This contrasts with the existing hypothesis that the pressure drop is roughly constant over different species.

[Phys. Rev. Fluids 11, 063102] Published Thu Jun 18, 2026

Author(s): Christiana Mavroyiakoumou, Jiajie Wu, and Leif Ristroph

Collective locomotion of swimming and flying animals is fascinating in terms of individual-level fluid mechanics and group-level structure and dynamics. Here we bridge and relate these scales through a formation-flight model that views the collective as a material whose properties arise from flow-mediated interactions among its members. Our model shows that the group behaves as a soft “crystal” with regularly spaced member “atoms” whose positioning is susceptible to deformations and dynamical instabilities. Other emergent properties relevant to biological collectives include group cohesion, sensitive detection of and response to perturbations, and information transfer through traveling waves.

[Phys. Rev. Fluids 11, 063103] Published Thu Jun 18, 2026

Author(s): Yunfan Huang and Moran Wang

Electrokinetic transport at liquid-liquid interfaces offers new routes for active microfluidic control, but practical use on slippery liquid-infused surfaces (SLIS) remains limited. Using direct numerical simulations, this work reveals two key regulation mechanisms, includign electroosmotic velocity reversal driven by groove oil depletion and a two-sided streaming potential effect from ion partition. These findings provide design principles for enhancing liquid pumping, energy conversion, and lab-on-a-chip devices in real-world multiphase systems.

[Phys. Rev. Fluids 11, 063702] Published Thu Jun 18, 2026

Author(s): Rémi Bousquet, Yannick Ponty, Victor Botez, Nicolas Plihon, and Caroline Nore

The von Kármán sodium experiment provided the first laboratory observation of magnetic field reversals reminiscent of those occurring in planetary dynamos. Using realistic numerical simulations robust across two independent solvers, we identify the mechanism underlying these reversals. The dynamics result from the coupling of dipolar and quadrupolar magnetic modes through two large-scale velocity modes, one of which breaks the flow symmetry. During a reversal, the magnetic field first localizes near one impeller, then evolves through a transient quadrupolar state before localizing near the opposite impeller and ultimately recovering as a dipole of reversed polarity.

[Phys. Rev. Fluids 11, 063703] Published Thu Jun 18, 2026