Physical Review Fluids

Author(s): Jianxun Huang and Ri Li

Bubble dynamics is critical for mass, momentum, and heat transport in two-phase flows. We investigated the effects of surface wettability on bubble formation, departure, and the surrounding liquid flow. Two-phase particle image velocimetry (PIV) captured the transient liquid-phase velocity field and instantaneous bubble shape. The experiments revealed strong wettability dependence in bubble size, departure frequency, and thus liquid phase flow dynamics. Applying finite difference analysis to PIV data, we further reconstructed time-resolved pressure, viscous stresses, and wall velocity gradients, enabling understanding of how wettability modulates the bubble-liquid interaction.

[Phys. Rev. Fluids 11, 023603] Published Thu Feb 12, 2026

Author(s): Andrea Montessori, Marco Lauricella, Aritra Mukherjee, and Luca Brandt

How a dispersed bubble phase reshapes turbulence remains a long-standing question, especially at moderate void fractions where coupling spans many scales. Using high-resolution lattice-Boltzmann simulations of forced homogeneous isotropic turbulence, we find that the global energy cascade stays close to Kolmogorov behavior up to 24% gas volume fraction. Phase-conditioned spectra, however, show a distinct gas-phase regime: a near-flat low-k range followed by a k−3 scaling at intermediate scales, consistent with localized bursts between two finite wavelengths. Our results separate universal transfer from phase-specific small-scale modifications in bubble-laden flows.

[Phys. Rev. Fluids 11, 024605] Published Thu Feb 12, 2026

Author(s): Iacopo Tirelli, Miguel Alfonso Mendez, Andrea Ianiro, and Stefano Discetti

A fully meshless approach enhances flow fields from sparse, randomly-positioned particle measurements. By merging information from locally similar snapshots over time, high-resolution, physically consistent velocity fields are reconstructed directly from scattered data without relying on grids at any step. Validated on experimental three-dimensional jet flow, the method reveals subtle structures and velocity derivatives that remain hidden to conventional techniques, providing a clearer, more faithful view of complex fluid dynamics.

[Phys. Rev. Fluids 11, 024902] Published Thu Feb 12, 2026

Author(s): J. O. Oyero, J. J. Hidalgo, M. Dentz, and A. De Wit

Buoyancy-driven instabilities strongly control mixing and reaction rates in stratified reactive fluids, yet how chemical reactions reshape the density field that drives these flows remains unclear. This work shows that a bimolecular reaction at a miscible interface can fundamentally alter density profiles, triggering convection even around initially stable stratifications and amplifying mixing in Rayleigh–Taylor unstable cases. By mapping flow regimes in terms of reactant and product density contributions, the study reveals how reactions govern instability onset, plume directionality, and overall reaction yield.

[Phys. Rev. Fluids 11, 024003] Published Wed Feb 11, 2026

Author(s): Huzaif Rahim, Sudeshna Roy, and Thorsten Pöschel

Granular materials composed of elongated particles exhibit morphological inhomogeneity under shear, driven by the interplay between particle alignment and dilatancy. Using discrete-element simulations in a linear split-bottom shear cell, we show how friction, particle shape, and initial packing conditions influence the steady-state surface morphology. Our results reveal that particle aspect ratio is the primary factor governing depression formation on the free surface, while friction localizes deformation within the shear band.

[Phys. Rev. Fluids 11, 024305] Published Wed Feb 11, 2026

Author(s): Valentin Skoutnev, Aurélie Astoul, and Adrian J. Barker

Inertial waves transport energy and momentum in rotating fluids, impacting mixing and tidal dissipation in Earth’s oceans, gaseous planets, and stellar interiors. This study examines the linear stability and nonlinear breakdown of finite-amplitude propagating plane inertial waves. We use numerical simulations to validate the frequency-dependent anisotropy of the most unstable perturbations predicted by linear Floquet theory and explore how the wave energy is partitioned between being dissipated in a cascade and accumulated in long-lived geostrophic modes.

[Phys. Rev. Fluids 11, 024802] Published Wed Feb 11, 2026

Author(s): Md Mainul Islam, Seyed Mojtaba Tabarhoseini, Nicole Miller, Yu-Hsiang Lee, Aimee Sayster, Joshua B. Bostwick, Yuhao Xu, and Xiangchun Xuan

We investigate the influences of fluid shear thinning and shear thinning gradients on electrokinetic instability (EKI) in microchannel flows with conductivity gradients via the addition of xanthan gum (XG) polymer. We also perform a scaling analysis to account for the fluid shear thinning effect on the electric Rayleigh number in terms of a power-law model. The critical values of this dimensionless number for the onset of EKI exhibit similar variations to the threshold electric field across fluid configurations (i.e., shear thinning (ST)/Newtonian (N), ST/ST, N/ST) and XG concentrations.

[Phys. Rev. Fluids 11, 023702] Published Tue Feb 10, 2026

Author(s): Jake Buzhardt and Michael D. Graham

Controlling fluid flows to induce laminarization is a challenging task due to the chaotic nature of turbulent flows. We introduce the “minimal seed for relaminarization”: the smallest perturbation of a turbulent state that triggers laminarization without a chaotic transient. This minimal seed and its trajectory provide an efficient laminarization pathway out of the turbulent region of the state space. Using a nonlinear optimization framework in a nine-mode shear flow model, we compute the minimal seed for relaminarization, analyze the associated dynamical structures, and show that it provides a useful reference for developing a control to trigger relaminarization.

[Phys. Rev. Fluids 11, 023902] Published Tue Feb 10, 2026

Author(s): Kennedy Nexon Chagua Encarnación, Antoine Seguin, and Baptiste Darbois Texier

Collisions between grains in dense granular flows give rise to diffusive-like particle trajectories. Here, we extend this framework beyond spherical grains by experimentally investigating the dynamics of individual semi-rigid fibers immersed in an index-matched granular flow. We systematically examine the effects of fiber length, diameter, grain size, and shear rate on fiber motion. The fiber center of mass undergoes a diffusive dynamics, with a diffusion coefficient that increases as the fiber length decreases relative to the grain size. Finally, we propose an empirical relation linking the fiber diffusion coefficient to that of the surrounding grains and to fiber geometrical properties.

[Phys. Rev. Fluids 11, 024304] Published Tue Feb 10, 2026

Author(s): Nicola Savelli, Ali R. Khojasteh, Abel-John Buchner, Jerry Westerweel, and Willem van de Water

The Josephson-Anderson relation was originally conceived to understand drag in quantum fluids in which vorticity is quantized. Surprisingly, it also explains drag in classical fluids when vorticity is constantly being generated. Drag ensues when vortices cross the streamlines of the background potential flow.

[Phys. Rev. Fluids 11, 024701] Published Tue Feb 10, 2026

Author(s): Baha Al-Deen T. El-Khader, Pavlos P. Vlachos, and Melissa C. Brindise

Patient specific intracranial aneurysm flows are often assumed insensitive to head orientation, yet gravity can reshape secondary motion in complex geometries. Using time-resolved volumetric particle tracking velocimetry (PTV) in patient-specific basilar tip and internal carotid artery models, we compare vertical and horizontal orientations under matched physiological inflow. Orientation altered streamline topology, vortex coherence, and wall shear parameters. These results quantify when orientation can (and cannot) be neglected in aneurysm hemodynamics.

[Phys. Rev. Fluids 11, 020501] Published Mon Feb 09, 2026

Author(s): Fumiya Tokoro, Hideki Takayama, Shinji Deguchi, Andreas Zöttl, and Daiki Matsunaga

How do planar beating microswimmers discover efficient swimming gaits under local energetic limits? Using reinforcement learning on a discretized bead–bend–spring filamentous microswimmer with locally constrained torques, we reveal emergent waveforms (frequency, amplitude, wavelength) set by a three-way competition between active torques, elastic stiffness, and the action-update interval. Our work offers a new framework for how local constraints determine optimum swimming patterns for undulatory locomotion.

[Phys. Rev. Fluids 11, 023102] Published Mon Feb 09, 2026

Author(s): Nihal Tawdi, Christophe Almarcha, and Michael Le Bars

Intermingling between buoyancy induced by a density gradient and externally imposed turbulence on propagation of a reactive interface is investigated through an autocatalytic reaction forming a thin front in an aqueous incompressible medium. Turbulence generated by oscillating grids, either spatially decaying or nearly homogeneous, allows flow effects to be isolated. Measurements with velocimetry and fluorescence reveal both the classical Huygens-type propagation and a reactive mixing regime where turbulent advection ignites dispersed reactions. Minute density variations are shown to influence front dynamics, highlighting a tight coupling between chemical kinetics and turbulent transport.

[Phys. Rev. Fluids 11, 024604] Published Mon Feb 09, 2026

Author(s): Tanu Singla, Jean-Baptiste Gorce, and Eric Falcon

Wave turbulence describes the dynamical properties of random nonlinear wavefields in infinite systems. Here, we experimentally investigate finite-size effects on gravity-capillary wave turbulence, using local magnetic forcing to generate a random, homogeneous wavefield – unlike previous studies that relied on oscillating tanks where global forcing dominates. We observe a smooth transition from continuous to discrete wave turbulence with increasing confinement, as finite-size effects weaken three-wave resonant interactions. This study bridges the gap between idealized infinite systems and confined environments, offering new insights into the role of boundaries in wave turbulence.

[Phys. Rev. Fluids 11, 024801] Published Mon Feb 09, 2026

Author(s): Dabao Li, Lang Qin, Zhigang Zuo, and Guangzhao Zhou

A chain of ascending bubbles can occasionally form stable, regular, and aesthetically striking patterns on a liquid’s free surface: a captivating phenomenon that also poses a fundamental challenge in fluid mechanics. This work establishes a framework linking the pattern morphology to the local dynamic interplays between the bubbles, the free surface, and the surrounding liquid flow. A heuristic model is proposed and validated against simulations and existing experimental data. The present study provides insights into understanding, designing, and controlling collective behaviors in broader self-organized systems.

[Phys. Rev. Fluids 11, 023602] Published Fri Feb 06, 2026

Author(s): Ming Hong, Beichen Tian, Qin Wu, and Biao Huang

Cavitation around marine propellers operating in nonuniform wake flows spans multiple spatial and temporal scales, yet its relationship to pressure pulsations is poorly understood. This study integrates pressure measurements with high-speed imaging and digital inline holography to resolve the evolution from large-scale sheet cavities and vortex tubes to intermediate-scale cloud clusters and microbubbles. We show that distinct cavitation regimes have characteristic spectra, with cloud cavitation producing the strongest multiscale coupling. By reconstructing phase-resolved microbubble statistics, a bubble model is developed that accurately reproduces mid- and high-frequency pressure components.

[Phys. Rev. Fluids 11, 024303] Published Fri Feb 06, 2026

Author(s): Georgy Zinchenko and Jörg Schumacher

Compressible turbulence adds further mechanisms of anomalous energy dissipation in comparison to its incompressible counterpart. They are caused by pre-shocks and shocks. To quantify these contributions, we extend the framework of Duchon and Robert to the compressible flow case and analyze anomalous dissipation for one-dimensional gas dynamics examples.

[Phys. Rev. Fluids 11, 024603] Published Fri Feb 06, 2026

Author(s): Mengfan Xu, Bowen Zhu, Zhanzhou Hao, and Bo Yin

Inspired by stiffness modulation in biological fish and advances in smart materials, we study the propulsion of a self-propelled swimmer with spatially nonuniform and dynamically varying stiffness. We demonstrate how different stiffness modulation strategies affect swimming performance and internal actuation requirements. By introducing a cycle-averaged equivalent stiffness, the required actuation strength can be consistently scaled across different modulation patterns.

[Phys. Rev. Fluids 11, 023101] Published Thu Feb 05, 2026

Author(s): Qingyang Meng and Chihyung Wen

This study investigates the characteristics of detonation structure and droplet behavior in n-heptane spray detonations where droplets experience a thermodynamic critical event, using the Eulerian-Lagrangian method. The droplet behavior at the critical state in the post-detonation area is captured and the resulting influence on the detonation structure and propagation is emphasized. The contribution of the droplet at the critical state to detonation is quantitatively estimated by the critical droplet fraction.

[Phys. Rev. Fluids 11, 023201] Published Thu Feb 05, 2026

Author(s): Bowen Du, Qi Li, Mingwei Ge, Xintao Li, and Yongqian Liu

In mesoscale modeling, wind turbines are commonly parameterized as single-column momentum sinks and sources of turbulence kinetic energy, which can lead to substantial errors when turbines are located near grid boundaries. This study proposes a Gaussian-based multi-column spatial distribution method that analytically allocates sink and source terms across multiple grid columns. When implemented within the Fitch wind farm parametrization, the proposed method significantly improves the modeling accuracy of wind farms, particularly when turbine rotors span multiple grid columns. The method provides a robust and physically consistent improvement for future mesoscale wind-farm simulations.

[Phys. Rev. Fluids 11, 023801] Published Thu Feb 05, 2026