New Papers in Fluid Mechanics

Author(s): Jianfeng Guo, Peng Kang, Kai Mu, and Ting Si

Altough many studies have focused on the aerobreakup of an isolated droplet, the coupling dynamics of multiple droplets remain less understood. By investigating the aerobreakup of parallel-arranged droplets under shock impact, this work systematically reveals how the decrease of droplet spacing induces breakup modes transition, i.e., from bag breakup to trailing and shuttlecock modes at low Weber numbers, and from open to closed configurations at high Weber numbers. Quantitative and theoretical analyses demonstrate that a reduced spacing accelerates the gas velocity between droplets, thus facilitating the homodromous bending and filament formation.

[Phys. Rev. Fluids 11, 023604] Published Tue Feb 17, 2026

Author(s): Christian Kankolongo, Didier Lasseux, Tony Zaouter, Florent Ledrappier, and Marc Prat

Predicting and controlling the liquid dynamics in a groove or grooved systems is of importance for various technological applications. Solutions for the flow of a wetting liquid in a channel of flattened triangular cross section are studied considering the combined effects of capillary imbibition and evaporation. Two main regimes are identified: the pure corner flow regime and the regime with partial bulk invasion. Situations where the mass transfer rate is independent of the external air relative humidity are exhibited for both regimes.

[Phys. Rev. Fluids 11, 024004] Published Tue Feb 17, 2026

Author(s): Qihao Yi, Zhigang Zuo, and Shuhong Liu

Unlike common cavitation flows, Venturi cavitation exhibits unique scaling due to its longitudinal pressure gradient. This study experimentally reveals four distinct cavitation patterns and their transitions with cavitation number and pressure recovery. A piecewise model combining Short and Extended Cavity theories, smoothed logarithmically, successfully predicts the cavity length. The established σ–κ mapping offers a practical tool for pattern identification and length prediction across Venturi geometries.

[Phys. Rev. Fluids 11, 024306] Published Tue Feb 17, 2026

Author(s): Shivani Prabala and Silas Alben

Which flow patterns are most effective at cooling hot boundaries? We address this question by optimizing incompressible two-dimensional fluid flows in a straight channel to maximize heat transfer under a fixed input power budget. Using an adjoint-based gradient framework combined with the Broyden–Fletcher–Goldfarb–Shanno (BFGS) optimization algorithm, we find that optimal flows remain predominantly unidirectional up to a critical Péclet number. Beyond this threshold, our improved numerical scheme uncovers a new class of wavy optimal flows. These flows are characterized by finger-like structures extending from the channel walls, which reorganize transport pathways and enhance thermal exchange.

[Phys. Rev. Fluids 11, 024502] Published Fri Feb 13, 2026

Author(s): L. Gudushauri, N. L. Shatashvili, G. Shekiladze, and S. M. Mahajan

This paper explores the catastrophic energy transformations, in particular the ones leading to the generation of a flow in a weakly rotating self-gravitating fluid/gas found, for instance, in the vicinity of a massive compact object. Because of the similarity in the governing equations, the system d…

[Phys. Rev. E 113, 025102] Published Fri Feb 13, 2026

Author(s): Joshua Ian Rawden, Christina Vanderwel, and Sean Symon

In our rapidly urbanizing world, an arms race has emerged between increasingly numerous polluting agents and the urban planners who model the behavior of these harmful gases. Physics-Informed Neural Networks (PINNs) have recently entered the space of data-driven fluids research as a tool for inferring physical fields from sparse and/or noisy measurements. This study aims to expand the existing use cases of PINNs by introducing them to the world of passive scalar transport through a low Reynolds number cylinder flow. The PINN is required to close the governing equations with limited data and unknown boundary conditions, thus demonstrating inference of previously unknown physical fields.

[Phys. Rev. Fluids 11, 024501] Published Thu Feb 12, 2026

Author(s): Wentao Pan and Qing Li

The transient response of Langmuir turbulence to an abrupt onset of surface heating is investigated using large eddy simulations. We show that the transient response of Langmuir turbulence is substantially different from wind-driven shear turbulence, with more gradual decay of turbulence intensity near the surface and much quicker response at depth. This is related to the more coherent downwelling plumes of Langmuir turbulence that extend throughout the surface boundary layer. The results have implications for improving Langmuir turbulence parameterizations that assume an equilibrium turbulence state with the surface forcing, which may fail in the early morning phase of a diurnal cycle.

[Phys. Rev. Fluids 11, 024606] Published Thu Feb 12, 2026

Author(s): Nathan Reyner, Chase T. Gabbard, and Joshua B. Bostwick

Experiments show that the presence of a buoyant particle layer on a liquid bath markedly changes the characteristics of an impulse wave generated by the subaerial collapse of a granular column. Relative to a clean interface, buoyant particles delay the transition from non-breaking to breaking waves with two distinct particle-accumulation regions emerging in the wave form: a static buildup adjacent to the collapsed grains that buttresses the pile, and a dynamic concentration zone traveling with the wave front that suppresses breaking. These results can provide potential insights into wave propagation in proglacial fjords laden with ice mélange or floating microplastic accumulations on the ocean.

[Phys. Rev. Fluids 11, 024803] Published Thu Feb 12, 2026

Author(s): Alberto Scotti

Fluid flows are usually described from a fixed point in space, while Lagrangian methods that follow the fluid often rely on particle trajectories embedded in a prescribed geometry. We develop a geometric formulation in which the observer moves with the fluid and the geometry of space itself evolves with the flow. This perspective naturally separates physical dynamics from observer effects, introduces geometric generalizations of inertial forces, and yields exact solutions and new stability results, including a proof of Couette flow stability at all Reynolds numbers.

[Phys. Rev. Fluids 11, 024901] Published Thu Feb 12, 2026

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