Latest papers in fluid mechanics

Author(s): Yuehongjiang Yu, Yang Yang, Jie Qi, Yu Qiu, Mengdi Sun, and Ke Xu

Bubble dissolution in porous media controls key applications including geological carbon sequestration, groundwater remediation, and energy engineering. The classic Epstein-Plesset model for bubble dissolution in open space is invalid in porous medium. We reveal how porous structure fundamentally reshapes dissolution, and derive analytical solutions for three typical bubble morphologies (single-pore, strip-shaped, and block-shaped). Analytical solutions are well verified by experiments and numerical simulations. Our new theory offers critical theoretical support for optimizing subsurface gas storage and gaseous pollutant removal technologies.

[Phys. Rev. Fluids 11, 053601] Published Fri May 01, 2026

Author(s): Xun Sun (孙逊), Zhizhong Zhou (周智忠), Weibin You (游炜彬), Sivakumar Manickam, Yunqiao Liu (刘筠乔), Wenlong Wang (王文龙), and Benlong Wang (王本龙)

We show that the incompressible Large eddy simulations of the condensation fronts (also referred to as bubbly shocks or condensation shocks) in partial cavitation within a three-dimensional Venturi agree well with the experiments. The condensation front is fundamentally different from traditional shock waves. The density variations due to evaporation and condensation of cavitation, rather than fluid compressibility, govern its formation and propagation. Hence, a compressible solver is unnecessary for simulating condensation fronts. These findings offer a new understanding of the shedding mechanism of partial cavitation.

[Phys. Rev. Fluids 11, 044304] Published Thu Apr 30, 2026

Author(s): Yutaro Motoori, Hideki Murahata, and Susumu Goto

We numerically investigate the swimming mechanism of a dolphin by focusing on the hierarchy of vortices in its turbulent wake. Using direct numerical simulations of a self-propelled dolphin and scale decomposition of the flow, we show that the caudal fin generates large vortex rings that contribute most of propulsion, whereas smaller vortices are created through the energy cascade but contribute little to propulsion. We also show that this mechanism remains robust regardless of the Reynolds number.

[Phys. Rev. Fluids 11, L042601] Published Thu Apr 30, 2026

Author(s): Bidisha Bhatt and Andreas Carlson

A droplet adopts a complex shape in a spring and can create significant spring compression, potentially functioning as a capillary weight-lifting system. By tuning the ratio between the pitch of the soft spring and the droplet size reveals a range of distinct droplet flow regimes, in which the vertical velocity is directly linked to the droplet’s rotational motion. Active control of the spring’s extension and compression demonstrates how both the static and dynamic states of the droplet can be controlled.

[Phys. Rev. Fluids 11, 043607] Published Wed Apr 29, 2026

Author(s): Chian Yeh Goh and Guillaume Blanquart

We revisit a largely overlooked theoretical model from Belen’kii and Fradkin (1965) and show that it captures many key features of non-Boussinesq Rayleigh-Taylor mixing observed in modern studies. By extending the analysis of this pioneering study, we uncover new physical insight and develop a practical, analytically tractable representation. Calibrated with DNS data, this work bridges classical theory and modern turbulence modeling, offering a compact tool for understanding and predicting variable-density turbulent flows.

[Phys. Rev. Fluids 11, 044501] Published Wed Apr 29, 2026

Author(s): Max Roccuzzo and Johann Herault

Surface-swimming organisms generate a rich variety of wave patterns. By studying the wakes produced by two juvenile snakes, we show that their surface waves strongly deviate from classical predictions for uniform straight-line motion. A simple slaloming-source model reproduces these patterns and shows they emerge from the superposition of translating, pulsating wave sources. Overall, our results provide a new framework for understanding capillary-gravity waves generated by non-uniform motion and enable the construction of a phase diagram describing these regimes.

[Phys. Rev. Fluids 11, 044805] Published Wed Apr 29, 2026

Author(s): Fabio Pino, Edoardo Fracchia, Benoit Scheid, and Miguel A. Mendez

Metallic coatings play a vital role in protecting metal surfaces from corrosion, but achieving uniform, defect-free layers remain a major challenge due to undulation instabilities. This work investigates a novel control strategy for liquid films on moving substrates using coordinated gas jets and electromagnetic actuators. By extending integral film models and embedding them in a reinforcement-learning framework, a proximal policy optimization (PPO) algorithm learns to actively suppress instabilities. The resulting control exploits a new physical mechanism: gas jets damp wave crests while electromagnetic forces lift troughs, leading to smoother coatings.

[Phys. Rev. Fluids 11, 044003] Published Tue Apr 28, 2026

Author(s): Henan Zhang, Hao Yang, Ziqi Cui, and Jun Zhang

In recent years, significant progress has been made in Fokker-Planck (FP) approximations of the Boltzmann equation, where binary collisions are modeled as drift and diffusion processes in velocity space. To address the discrepancy in the Prandtl number for the original linear FP model, several modif…

[Phys. Rev. E 113, 045107] Published Tue Apr 28, 2026

Author(s): Jinshun Gao, Xiaofeng Wei, Dege Li, Dongyao Wu, Lulu Pan, Dongyun Wang, Mingbo Li, Yuliang Zhang, and Benoit Scheid

We investigate the breakup dynamics of an inviscid liquid bridge under slow drainage. The transition from symmetric to asymmetric breakup occurs at a length-to-radius ratio of 4.1, corresponding to a shift from even-mode to odd-mode dominance. Contrary to previous experimental conclusions, we show that satellite droplet momentum originates from capillary impulses beginning at the flattening moment before the first pinch-off. A new scaling law is proposed and validated.

[Phys. Rev. Fluids 11, 043606] Published Mon Apr 27, 2026

Author(s): Jialiang Sun, Ning Huang, Binbin Pei, and Jie Zhang

Vegetation canopies in open-channel flows often experience time-dependent drag that reshapes turbulence near the canopy top. Using large-eddy simulation with a variable-drag model, we show that oscillatory drag reorganizes coherent vortices and shifts turbulent kinetic energy activity from the canopy-top shear layer into the canopy interior. The framework provides an efficient way to isolate how prescribed canopy drag affects turbulence structure and energy transport in large-domain simulations.

[Phys. Rev. Fluids 11, 044610] Published Mon Apr 27, 2026

Author(s): Chunxin Yuan, Shuying Zhang, Zhan Wang, and Xueen Chen

The Fully Dispersive Internal Wave (FDIW) equations, related on the two interface fluctuations in three-layer fluid, is derived from the stratified Euler equations using multiscale asymptotic expansion valid up to second-order nonlinearity. It can accommodate both mode-1 and mode-2 nonlinear internal waves and their transformations without further assumptions like the comparable phase speed of two modes needed in the well-known coupled Korteweg-de Vries (KdV) system, due to capturing all wavelengths without long-wave assumptions. The results indicate that coupled KdV equations should be used in the ocean with great caution as the difference between the KdV and FDIW equations is shown.

[Phys. Rev. Fluids 11, 044804] Published Mon Apr 27, 2026

Author(s): Hugo A. Castillo-Sánchez, Weston Ortiz, Richard Martin, Rukiye Tuna, Rekha R. Rao, and Z. Leonardo Liu

Blood flow in microcirculation exhibits complex, non-Newtonian behavior arising from red blood cell (RBC) migration and the formation of a near-wall cell-free layer (CFL), which remain challenging to capture with continuum models. Here, we introduce a modified suspension-balance model with a lift-force closure that bridges cell-level microrheology to continuum transport. The model quantitatively predicts CFL formation, hematocrit redistribution, and velocity blunting, while recovering key physiological signatures. This work provides an efficient continuum framework for capturing heterogeneous transport in concentrated deformable particle suspensions under confinement.

[Phys. Rev. Fluids 11, 043102] Published Fri Apr 24, 2026

Author(s): Kepeng Yao, Wenbin Liao, Guilai Han, and Zonglin Jiang

Oblique detonation waves are pivotal for hypersonic propulsion, but their stationary characteristics are rarely studied under controlled reaction rate distributions. Two-dimensional Euler simulations coupled with a two-step kinetic model are employed, and the effects of activation energy and reaction rate constant are isolated while induction and exothermic zone lengths are fixed. It is demonstrated that higher activation energy delays initiation and stabilizes oblique detonation, while unsteady upstream motion via thermal choking is triggered when a critical reaction rate is exceeded. A new stability criterion for oblique detonation is provided by these results.

[Phys. Rev. Fluids 11, 043202] Published Fri Apr 24, 2026

Author(s): Bikash Mohanty, Angshuman Nayak, and Aditya Bandopadhyay

We investigate the dynamics of a leaky dielectric droplet subjected to a superposed alternating and constant electric field using analytical small deformation theory and phase-field simulations. The mean and amplitude of droplet deformation depend on the mixing ratio (MR) and frequency of the superposed electric field. Results show that deformation amplitude under a superposed field is larger than in a purely alternating electric field. When the root-mean-square value of the superposed field exceeds that of the pure AC field, the mean deformation increases with increasing MR. The variation of the nondimensional oscillating interfacial kinetic energy with MR is also explored.

[Phys. Rev. Fluids 11, 043703] Published Fri Apr 24, 2026

Author(s): Weihao Ling, Zhiheng Wang, Zhenfei Wang, Wenlin Huang, and Guang Xi

We investigate the bypass transition of a flat-plate boundary layer over a three-dimensional irregular rough surface characterized by isotropic protrusions and a favorable-adverse pressure gradient. By positioning the roughness upstream of or adjacent to the separation point and introducing inlet free-stream turbulence of varying intensities and fundamental frequencies, the combined effects of pressure gradients, three-dimensional roughness, and free-stream turbulence on bypass transition and disturbance amplification are examined. Notably, when the rough surface is upstream of the separation point, intense low-frequency free-stream turbulence can excite novel elongated resonant modes.

[Phys. Rev. Fluids 11, 043905] Published Fri Apr 24, 2026

Author(s): Yuan Li and Chenglong Tang

Unlike-doublet impinging jets are widely used in hypergolic liquid rocket engines, but the role of inertia disparity in shaping atomization and mixing has remained unclear. Using high-fidelity Volume of Fluid simulations with intra-liquid species transport, we show that increasing inertia disparity narrows the spray, shortens liquid-sheet breakup, and reduces mixing efficiency. At high disparity, the jets exhibit central-axis collapse and mutual penetration, producing a distinctive flow-rate distribution. Flow topology analysis links these behaviors to Kelvin–Helmholtz type shear instabilities that generate vortices and drive liquid sheet collapse.

[Phys. Rev. Fluids 11, 044303] Published Fri Apr 24, 2026

Author(s): Rohini Uma-Vaideswaran and P. K. Yeung

The second-order Lagrangian velocity structure function in turbulence is a fundamental quantity for which clear inertial range scaling has been much more elusive than corresponding Eulerian measures. In this work direct numerical simulation at high Reynolds number is used to better understand the question of asymptotic constancy of the supposed scaling constant through effects of the acceleration autocorrelation function. A spatial-temporal decomposition of the Lagrangian velocity increment exposes strong but incomplete cancellation between convective and local contributions, with rapid approach of particle displacements towards inertial range values having an important role.

[Phys. Rev. Fluids 11, 044607] Published Fri Apr 24, 2026

Author(s): Taihang Zhu, Chao Xia, Jiabin Pang, Olivier Cadot, and Jonathan F. Morrison

We introduce a momentum decomposition framework to analyze the pressure field. It establishes a generic relationship between the mean pressure and flow statistics for turbulent flow, manifesting as fundamental mechanisms of pressure-gradient contributions in Cartesian coordinates involving mean flow accelerations, Reynolds stresses, and viscous stresses. With a focus on bluff body flows, this framework is validated in both laminar and turbulent regimes, providing a physical basis for flow analysis and control.

[Phys. Rev. Fluids 11, 044608] Published Fri Apr 24, 2026

Author(s): Xiaodong Wu, De Li, and Zhiming Lu

Counter-gradient transport in stably stratified shear turbulence remains poorly understood, particularly from a structural perspective. Using direct numerical simulations combined with the clustering method, this study identifies and characterizes coherent structures responsible for counter-gradient transport of heat and momentum. We find that such transport is dominated by structures larger than the Corrsin scale and primarily organized as paired Q1–Q3 events. Distinct physical mechanisms are revealed, with heat transport arising from both vortex-induced rotation and fluid parcel interactions, while momentum transport is governed solely by vortex-induced rotation.

[Phys. Rev. Fluids 11, 044609] Published Fri Apr 24, 2026

Author(s): Frederik R. Gareis and Walter Zimmermann

Outward-diffusing vorticity fields form around particles and droplets in time-periodic fluid motions. As a result, the time-dependent shear gradients in the fluid and at the particle surface are typically greater than those of the classical steady-state Stokes velocity profile. This leads to an additional viscous force, the Basset–Boussinesq history force (BBH), which depends on the past motion of the particle that created the vortices. An experiment with particles in a shaken fluid is proposed to measure the parameter dependence of the BBH, and parameter ranges are also predicted in which the BBH becomes comparable to or stronger than classical Stokes friction.

[Phys. Rev. Fluids 11, 043604] Published Wed Apr 22, 2026