Physical Review Fluids

Author(s): Eric Ibarra, Fabien Candelier, and Gautier Verhille

From previous studies on rigid isotropic particles, one might expect that heavy particles would be centrifuged out of vortices. However, during experimental runs, we observed thin, heavy, flexible discs trapped in stable orbits near a vortex core. By reconstructing their three-dimensional shape and motion, we show how deformability and anisotropy alter the classical force balance. The results raise new questions about how form and flexibility impact transport in vortical flows.

[Phys. Rev. Fluids 11, 044302] Published Mon Apr 06, 2026

Author(s): Kirill Goncharuk, Saichand Chowkampally, Yuri Feldman, and Oz Oshri

The relaxation of a buckled elastic sheet in a fluid involves a balance between bending, inertia, and hydrodynamic forces. We show that a minimal inviscid model predicts both the oscillation frequency about the stable mode and the growth rate of unstable modes, in agreement with more general viscous simulations. The framework also captures the temporal transition from unstable to stable configurations.

[Phys. Rev. Fluids 11, 044401] Published Mon Apr 06, 2026

Author(s): Zishuo Han, Weiyu Shen, and Yue Yang

We model turbulence using coherent vortices distributed within a multiscale statistical framework, termed woven turbulence, which naturally captures key turbulence features. Based on explicitly controllable vortices, we find that the scale-independent hierarchical vortex density corresponds to the −5/3 law of the energy spectrum, while the Reynolds-number-independent total vortex density corresponds to the intermittent scaling of the structure function. Woven turbulence also serves as a fast turbulence synthesis method, requiring only the Taylor-Reynolds number as input and exhibiting extremely low computational cost comparable to the random Fourier modes method.

[Phys. Rev. Fluids 11, 044602] Published Mon Apr 06, 2026

Author(s): Prem Chand Chandolu and Balachandra Suri

Horizontally driven shallow electrolyte flows are widely employed laboratory analogs of oceanic and two-dimensional flows. Although previous studies investigated the presence of three-dimensional circulations within the bulk of turbulent shallow flows, relatively little attention was paid to whether the fluid layer thickness itself remains spatiotemporally uniform. In this study, we report experimental measurements of free-surface deformations in shallow flows. For certain Reynolds number and fluid layer height combinations that characterize the flow, we show that the free surface undergoes significant deformation, thereby rendering an otherwise shallow flow geometrically three-dimensional.

[Phys. Rev. Fluids 11, 044801] Published Mon Apr 06, 2026

Author(s): Qiwei Chen and C. Ricardo Constante-Amores

Rayleigh–Bénard convection is a canonical system for studying turbulent heat transport, yet controlling it at high Rayleigh numbers remains computationally prohibitive. Here, we combine data-driven manifold dynamics with reinforcement learning to construct a reduced-order environment that enables efficient training of control policies. When deployed in direct numerical simulations, the learned strategies achieve up to 23% reduction in heat transfer by stabilizing near-wall dynamics and suppressing plume emission. This work establishes a scalable and physically interpretable route to controlling high-dimensional turbulent flows.

[Phys. Rev. Fluids 11, 044903] Published Mon Apr 06, 2026

Author(s): Githin Tom Zachariah and Harry E. A. Van den Akker

The Lattice Boltzmann Method (LBM) exploits its nearly incompressible nature to relate local density to pressure, avoiding iterative Poisson solvers. However, this pressure–density coupling makes robust extension of LBM to the Two-Fluid equations particularly challenging. In this work, we propose two complementary approaches to address this problem: a mixture model for dilute suspensions prioritizing computational efficiency, and a well-balanced formulation employing a pressure-free LBM with an explicit Poisson solver for maximum accuracy. Both methods are validated on standard benchmarks and isotropic turbulent flows, demonstrating accuracy and robustness across challenging flow regimes.

[Phys. Rev. Fluids 11, 044904] Published Mon Apr 06, 2026

Author(s): Marco Raiola and Jochen Kriegseis

Advective flows are often characterized by wavepackets. Hilbert proper orthogonal decomposition (HPOD) extracts these coherent structures from flow field data by exploiting their representation as modulated traveling waves. HPOD is a complex valued extension of proper orthogonal decomposition, where the analytic signal is obtained via a Hilbert transform applied either in time (conventional HPOD) or along the advection direction (space-only HPOD). Both HPOD formulations yield equivalent decompositions for advecting wavepackets. The resulting modes exhibit amplitude and frequency modulation in space and time, enabling instantaneous, local flow analysis.

[Phys. Rev. Fluids 11, 044905] Published Mon Apr 06, 2026

Author(s): Ankit Gautam and Tim Berk

The decay of turbulent kinetic energy is strongly influenced by large-scale coherent structures. Using a synthetic-jet-driven turbulence facility and the Proper Orthogonal Decomposition (POD) method, we show that slowly decaying modes persistent across repeated experiments bias the observed decay rates. Removing these modes reveals a stochastic turbulence field with decay consistent with classical theory. This framework helps resolve discrepancies in reported decay rates and distinguishes whether variations arise from specific coherent modes or changes in the underlying stochastic turbulence.

[Phys. Rev. Fluids 11, 044906] Published Mon Apr 06, 2026

Author(s): Niccolò Tonioni, Lionel Agostini, Franck Kerhervé, Laurent Cordier, and Ricardo Vinuesa

Sparse-sensing reconstruction of turbulent flows remains challenging due to high sensor requirements and poor fidelity near solid interfaces. VIVALDy, a machine learning framework, addresses these limitations through a hybrid β-Variational Autoencoder-Generative Adversarial Network (β-VAE-GAN) and a bidirectional transformer to compress flow fields into a compact latent space and predict temporal evolution from minimal inputs. Masked convolutions are used to enhance fidelity at solid boundaries. Validated against experimental data for a moving cylinder, the framework reconstructs diverse fluid-structure interaction regimes using only cylinder displacement.

[Phys. Rev. Fluids 11, 044902] Published Fri Apr 03, 2026

Author(s): Haojun Zhao, Wei Wang, Sheng Xu, and Bing Wang

When a cylindrical droplet containing a solid particle rod interacts with a planar shock wave, a complex evolution of its internal wave structure ensues. We simulate the interaction numerically, and the ray analysis method is specifically adopted to analyze the evolution of the wave structure in detail. The results show that the particle rod separates negative pressure regions more distinctly, raises the droplet’s minimum pressure, leads to cavitation at high shock wave intensity, and that particle eccentricity influences wave structure and cavitation. These findings are expected to contribute to advancements in fuel atomization and biomedical applications.

[Phys. Rev. Fluids 11, 044301] Published Thu Apr 02, 2026

Author(s): Santiago J. Benavides and Miguel D. Bustamante

The transfer of energy and other conserved quantities across scales is a central aspect of out-of-equilibrium systems such as turbulent hydrodynamic flows. Despite its role in the few predictive theories that exist, a dynamical understanding of what determines said transfer (and its direction in scale) has yet to be established. In this study, we investigate how the dynamics of complex Fourier velocity phases influence the flux of conserved quantities in simplified (“shell”) models of hydrodynamic turbulence. We develop an analytically tractable model for the statistics of the phases, validate the model using simulations, and use the model to predict properties of the energy cascade.

[Phys. Rev. Fluids 11, 044601] Published Thu Apr 02, 2026

Author(s): Alireza Khoshnood, Vedad Dzanic, Zhongzheng Wang, and Emilie Sauret

Viscoelastic natural convection differs from its purely Newtonian analogue due to polymer-induced elastic stresses and shear-dependent viscosity. When coupled to buoyancy-driven flow, these viscoelastic effects modify velocity and thermal boundary layers. We examine the role of cavity aspect ratio in governing the spatial distribution of elastic stresses. Coupled effects of cavity aspect ratio and viscoelasticity determine whether polymer forces enhance or suppress convection, thus affecting local and overall heat transfer performance. These insights offer guidance for controlling heat transfer under low-inertia, with implications for thermal management and process design in polymeric flows.

[Phys. Rev. Fluids 11, 043501] Published Wed Apr 01, 2026

Author(s): Yasushi Mino, Hazuki Tanaka, Koichi Nakaso, Kuniaki Gotoh, and Rei Tatsumi

Numerical simulations of sheared particle suspensions often require large domains to avoid wall effects. We implement Lees–Edwards boundary conditions in particle-resolved Lattice Boltzmann Method–Discrete Element Method (LBM–DEM) simulations to model homogeneous shear flows without physical boundaries. The method enables computationally efficient simulations while resolving particle-scale hydrodynamic interactions. It provides a practical tool for studying suspension rheology quantitatively by capturing how particles interact with the surrounding fluid and with each other across a range of concentrations.

[Phys. Rev. Fluids 11, 044901] Published Wed Apr 01, 2026

Author(s): Reza Azadi and David S. Nobes

While drag reduction in fully developed viscoelastic flows is widely studied, the combined influence of polymer additives and strong spatial acceleration remains largely unexplored. This study employs high-resolution velocimetry to examine near-wall turbulence in semidilute polymer solutions subjected to varying favorable pressure gradients. The results demonstrate that the interplay of viscoelasticity and acceleration profoundly suppresses Reynolds shear stresses, driving the boundary layer toward a distinct quasi-relaminarized state dominated by elastic effects.

[Phys. Rev. Fluids 11, 034611] Published Tue Mar 31, 2026

Author(s): Saideep Pavuluri, Thomas Daniel Seers, Ali Saeibehrouzi, Ran Holtzman, Soroush Abolfathi, Petr Denissenko, and Harris Sajjad Rabbani

Controlling capillary fingering via patterned porous media (PPM) optimizes industrial processes (e.g., fuel cells). We introduce a 2D Zoned Sequential Deposition method to fabricate PPM with tunable porous media features. Direct numerical simulations across varying capillary numbers and heterogeneity factors show that highly heterogeneous PPM (having larger pore-diameter contrasts between different zones) promotes structured drainage: flow follows underlying porous microstructure, draining through large pores with less than 10% occupancy of finer spaces. This coupling of fabricated morphology and flow behavior provides a framework for designing porous materials with predictable flow patterns.

[Phys. Rev. Fluids 11, 034001] Published Thu Mar 26, 2026

Author(s): M. Noseda, B. L. Español, P. D. Mininni, and P. J. Cobelli

Helicity, the volume integral of the velocity-vorticity scalar product, is a key dynamical invariant encoding flow topology; however, measuring it in turbulence is a significant challenge due to the requirement for high-resolution velocity gradients. We introduce chirality tomography, a Lagrangian method that reconstructs three-dimensional helicity maps from the entanglement of particle trajectories. By establishing a robust proxy between trajectory linking and local helicity, we provide the first spatially resolved maps of chiral structures in fully developed turbulence. The approach bridges trajectory-level topology with fundamental physics, with a practical diagnostic for complex flows.

[Phys. Rev. Fluids 11, 034609] Published Wed Mar 25, 2026

Author(s): G. A. Gerolymos and I. Vallet

In turbulent flows of dilute gases, the amplitudes and correlations of the turbulent fluctuations of the thermodynamic variables (pressure, density and temperature), satisfy exact nonlinear compatibility relations and inequalities. These define realizability constraints on the thermodynamic turbulence structure, valid from the quasi-incompressible-flow limit to hypersonic Mach numbers. Furthermore, the ratios between fluctuation intensities define the signs of correlations between the thermodynamic fluctuations, and define bivariate mappings of the thermodynamic turbulence structure.

[Phys. Rev. Fluids 11, 034610] Published Wed Mar 25, 2026

Author(s): Bapan Mondal, Shubhra Sahu, and Somnath Bhattacharyya

Present continuum based modified electrokinetic model capture the nonclassical pattern of the electric double layer arises in the strong coupling regime i.e., layered structure of ions, counterion saturation, overscreening of surface charge, and reversal in electroosmotic flow. Based on the present modified model we have established qualitative agreement with several experimental observations, which the mean-field based models fails to envisage. The short-range effects on ion transport and their impact on membrane polarization are quantified in this study, which has not been addressed in previous studies. It may provide useful insights on tuning the electroosmosis and particle trapping.

[Phys. Rev. Fluids 11, 034202] Published Tue Mar 24, 2026

Author(s): Pritpal Matharu, Bartosz Protas, and Tsuyoshi Yoneda

A key open question in turbulence research concerns the nature of fluid motions that can produce a self-similar energy cascade consistent with Kolmogorov’s statistical theory of turbulence. We approach this problem by considering the one-dimensional viscous Burgers equation as a toy model, and frame the question in terms of a family of partial-differential-equation-constrained optimization problems which are solved numerically. Our results represent a successful effort to construct time-dependent solutions of this model characterized by self-similar energy transfers, providing a framework that may be used to search for self-similar behavior in three-dimensional turbulence.

[Phys. Rev. Fluids 11, 034608] Published Mon Mar 23, 2026

Author(s): Yicong Fu, Zhengyang Liu, Samir Tandon, Jake Gelfand, and Sunghwan Jung

Flexible vortex generators enhance heat and mass transport, but most studies focus on solid, non-porous panels or passive flexible reeds. Inspired by porous, compliant fish-gill filaments, we demonstrate the mixing benefit of pitching flexible perforated panels. Pitching drives unsteady entrainment; perforation yields spatially discretized vortices without a conventional leading-edge contribution, while chord-wise flexibility sustains mixing via wake-mode transitions. We examined the Lagrangian coherent structures to link vortex dynamics to convective–diffusive transport, and proposed three indices to quantify mixing by uniformity, mean increase, and spatial dispersion.

[Phys. Rev. Fluids 11, 034703] Published Mon Mar 23, 2026