Latest papers in fluid mechanics

Author(s): Xiantao Fan, Meet Hemant Parikh, Yi Liu, Xin-Yang Liu, Junyi Guo, Meng Wang, and Jian-Xun Wang

Most studies of turbulent wall pressure reduce its dynamics to wavenumber-frequency spectral descriptions, leaving the instantaneous, spatially evolving pressure field largely inaccessible to experiments and prohibitively expensive simulations. We introduce a probabilistic generative approach that reconstructs full spatiotemporal wall-pressure fields from sparse surface measurements and a low-cost mean-pressure descriptor. Combining patchwise neural representations with latent diffusion, the model adapts to unseen sensor layouts and pressure-gradient regimes without retraining. It recovers coherent structures, temporal evolution, and key turbulence statistics.

[Phys. Rev. Fluids 11, 084607] Published Thu Aug 13, 2026

Author(s): Vikas S. Krishnamurthy and Takashi Sakajo

The stationary equilibria of N point vortices in a rectangular domain with doubly periodic boundary conditions offer a foundational framework for understanding the stationary lattices of coherent vortex structures. In this paper, we obtain new continuous families of these lattices. These solutions a…

[Phys. Rev. E 114, 025105] Published Thu Aug 13, 2026

Author(s): Albert Dai and Yu-Lin Huang

When gravity currents converge inward, such as sea breezes closing in around an island or lake, their collision unfolds very differently from the situation when two gravity currents meet head-on. Using high-resolution three-dimensional simulations, this study reveals, for the first time, how such collisions generate turbulence: vorticity arises primarily through tilting of azimuthal vorticity rather than through the stretching mechanism as seen in planar collisions. The resulting eddy diffusivity data support existing mesoscale-model parameterizations used to represent gravity current collision events in atmospheric and oceanic models.

[Phys. Rev. Fluids 11, 083801] Published Wed Aug 12, 2026

Author(s): Tino Damiani, Matthew Durey, Bauyrzhan K. Primkulov, and John W. M. Bush

A millimetric droplet may walk across the surface of a vibrating liquid bath, self-propelled by its own wave field. This pilot-wave hydrodynamic system has provided the basis for the field of hydrodynamic quantum analogs, the goal of which is to redefine the boundaries between classical and quantum systems. We here deepen our understanding of pilot-wave hydrodynamics through consideration of its energetics, evaluation of the partitioning between droplet and wave energies. Photo credit: Pedro Nachbin.

[Phys. Rev. Fluids 11, 084002] Published Wed Aug 12, 2026

Author(s): D. M. Escala, I. Castaldi, and A. De Wit

Previous theoretical works showed that, in double-diffusion regimes, the onset time and mixing velocity of convective fingers are controlled by a dynamic density jump across stratified layers. Here, we experimentally validate these scalings by analyzing differential diffusion-induced convection in horizontal stratifications within a Hele-Shaw cell. Using a wide range of solute combinations and concentrations, we vary the two key parameters of the problem: the diffusion coefficient and buoyancy ratios. We show that, in both double-diffusive and diffusive-layer-convection regimes, convective dynamics are governed by dynamically generated local adverse density jumps.

[Phys. Rev. Fluids 11, 084502] Published Tue Aug 11, 2026

Author(s): Flavio Tuteri, Sergio Chibbaro, and Alexandros Alexakis

Classical shell models of turbulence fail to reproduce the dual energy–enstrophy cascade of two-dimensional flows because they predict the wrong equilibrium spectra. Introducing a hierarchical spatial organization across scales restores the correct equilibrium scaling and leads to a statistically stationary dual cascade. The resulting model consistently captures both the equilibrium properties and the nonequilibrium cascade dynamics of two-dimensional turbulence.

[Phys. Rev. Fluids 11, 084604] Published Tue Aug 11, 2026

Author(s): Xiangyu Nie and Shengkai Wang

We report direct experimental observations of self-sustaining CH4–air flames rotating along the edge of an unheated circular Hele-Shaw cell, extending beyond previous studies in which such flames were observed only under external heating. Formed under fuel-rich conditions, these flames exhibit stable traveling-wave behavior, with edge velocities exceeding nominal laminar flame speeds and a structure comprising both premixed and diffusion branches. The rotation arises from a balance between local flame speed, flow, and wall heat loss. Parametric studies have identified regimes of single and multiple rotating waves, as well as transitions to ring flames or extinction under extreme conditions.

[Phys. Rev. Fluids 11, 083201] Published Mon Aug 10, 2026

Author(s): Suruj Kalita and Rajaraman Ganesh

We investigate subcritical turbulence in plane Couette flow using a finite-amplitude columnar vortex instead of the conventional Lundbladh-type perturbation. We show that, although the perturbation modifies the turbulent structure, the key characteristics of subcritical turbulence remain unchanged. The figure illustrates the breakdown of the columnar vortex into tripolar and quadrupolar structures in unstratified and stably stratified flows. The columnar vortex breakup provides a new mechanism for streamwise streak formation.

[Phys. Rev. Fluids 11, 083301] Published Mon Aug 10, 2026

Author(s): Pratyush Kumar Mohanty, P. S. D. Surya Phani Tej, Gade Sanjana, and V. Shankar

We revisit the classical hoop-stress mode (HSM) instability in viscoelastic Taylor-Couette flow using the FENE-P model. We show how finite polymer extensibility modifies the onset of the hoop-stress mode for a range of gap width ratios. By systematically comparing linear stability predictions with experiments and direct numerical simulations, we identify where the model succeeds and where its limitations emerge and what are the possible reasons for the discrepancies. We also compare our linear stability results with an augmented Pakdel–McKinley criterion that incorporates finite extensibility and finite gap effects.

[Phys. Rev. Fluids 11, 083302] Published Mon Aug 10, 2026

Author(s): Meng Fan, Antoine Dazin, Gérard Bois, and Francesco Romanò

Low-flow-rate instabilities in vaneless diffusers remain a long-standing challenge in turbomachinery, with the roles of core-flow dynamics and boundary layers still debated. Using a hierarchy of linear stability analysis and two- and three-dimensional URANS simulations, we identify two distinct instability mechanisms and trace them back to their physical origins. The low-flow-rate instability is shown to arise from a two-dimensional inviscid core-flow mechanism, while a new instability, associated with inlet modulation and three-dimensional flow features, is reported at high flow rates.

[Phys. Rev. Fluids 11, 083902] Published Mon Aug 10, 2026

Author(s): Gourab Saha and Kajal Kumar Mondal

Reactive solute transport in open-channel flows is central to understanding contaminant migration in rivers, wetlands, and engineered waterways, but the combined influence of wind-induced shear, porous-bed resistance, and wall absorption has remained unresolved. This study introduces a generalized dispersion model that captures the coupled transient effects of those three influences through analytical transport coefficients and concentration distributions, validated by Brownian dynamics simulations. The findings reveal how wind direction governs pollutant dispersion, retention, and removal, and provides a predictive framework for layered environmental flows.

[Phys. Rev. Fluids 11, 084501] Published Mon Aug 10, 2026

Author(s): Francesco Carbone and Sergio Servidio

In this work, we analyze two-dimensional turbulence in a Galerkin-truncated system with pseudo-logarithmic and random mode selection in Fourier space. The results confirm the presence of the double energy cascade (k−5/3 and k−3) and show how anisotropy influences the organization of vorticity without altering universal scaling laws. Finally, particle pair dispersion follows Richardson superdiffusion (ℓ2(t)∼t3), demonstrating that preserved spectral interactions sustain turbulent transport.

[Phys. Rev. Fluids 11, 084603] Published Mon Aug 10, 2026

Author(s): Conan M. Liptrott, Sandra C. Chapman, Bogdan Hnat, and Nicholas W. Watkins

A scale-by-scale analysis of energy flux in the turbulent cascade can be performed using the spatially filtered magnetohydrodynamic (MHD) equations, while the gradient tensor invariants are widely used to characterize the structure of velocity and magnetic fields. Physical mechanisms responsible for…

[Phys. Rev. E 114, 025102] Published Mon Aug 10, 2026

Author(s): Radha S, Swarup Barik, and Sourav Hossain

This study presents an analytical solution of the two-dimensional concentration distribution of a contaminant in a channel with a prismatic cross-section and asymmetric velocity distribution, influenced by reversible and irreversible reactions, along with the bulk chemical reaction. Recent works by …

[Phys. Rev. E 114, 025103] Published Mon Aug 10, 2026

Author(s): Yuxing Jiao and Mingcheng Yang

Odd fluids are a class of fluids characterized by nonzero antisymmetric transport coefficient tensors induced by broken time-reversal symmetry. In our previous work, a mesoscale simulation model for two-dimensional isotropic odd fluids was developed. Here, we extend the model to the three-dimensiona…

[Phys. Rev. E 114, 025104] Published Mon Aug 10, 2026

Author(s): Wanqiu Zhang, Fei Zhang, and Xinping Zhou

Capillary attachment is a fundamental phenomenon in microengineering, yet the lack of comprehensive theories makes it difficult to predict a pendant drop’s particle-lifting capability. We investigate the critical roles of stability in this process, specifically addressing how to maximize lifting capacity. Our work establishes the theoretical framework required to successfully lift particles in practical applications.

[Phys. Rev. Fluids 11, 084001] Published Fri Aug 07, 2026

Author(s): Debanik Bhattacharjee, Guy Z. Ramon, and Yaniv Edery

Capillarity-dominated two-phase displacement in porous media can continue beyond the initial invasion-percolation (IP) breakthrough when surfactants progressively modify interfacial properties and reopen pathways previously sealed by capillary barriers. We study this post-breakthrough secondary inva…

[Phys. Rev. E 114, 025101] Published Thu Aug 06, 2026

Author(s): Suraj Kumar Nayak, Vishwanath Shukla, and Akshay Bhatnagar

Direct numerical simulations reveal the orientation and transport of spherical, spheroidal, and rod-like gyrotactic microswimmers in three-dimensional turbulence. Strongly gyrotactic swimmers preferentially align with the vertical, while weakly gyrotactic swimmers are nearly isotropic. Rod-like swimmers are more strongly affected by fluid shear and align with the principal strain direction. Orientation correlations depend on the gyrotactic response time, and all shapes transition from ballistic to diffusive transport. A reduced two-dimensional model for spherical swimmers reproduces the key statistics.

[Phys. Rev. Fluids 11, 084602] Published Tue Aug 04, 2026

Author(s): Avraham Moriel, Howard A. Stone, and Simon Mendez

The ability of red blood cells to deform under shear flow is critical to cardiovascular function, yet capturing their complex fluid-structure interactions remains challenging. We extend a perturbative approach to capture cellular enucleation, and probe the emergence of shape instabilities under shear flow. This method isolates how a cell’s initial orientation, membrane mechanics, and viscosity contrast drive morphological instabilities, such as stomatocytes and trilobes. Ultimately, this framework provides a baseline for understanding how disorders like sickle cell disease and malaria compromise cells dynamics.

[Phys. Rev. Fluids 11, 083601] Published Mon Aug 03, 2026

Author(s): Cheng-Quan Fu, Zongqiang Ma, Yang Song, Cunbo Zhang, Sijia Lyu, Chenyue Xie, Anmin He, Nan-Sheng Liu, and Pei Wang

Rayleigh-Taylor mixing is important in natural phenomena and engineering applications, but limited spatial resolution in practical experiments and simulations constrains studies of this mixing process. Resolution-limited fields preserve only large-scale features such as mean profiles and mixing widths, but fail to resolve small-scale structures, resulting in lower fluctuation variance and higher apparent mixedness. Convolutional neural network (CNN) based superresolution reconstructs multiscale flow fields and recovers mixedness evolution, with robust generalization across unseen phases and flow parameters.

[Phys. Rev. Fluids 11, 083901] Published Mon Aug 03, 2026