New Papers in Fluid Mechanics

Author(s): Alexei A. Mailybaev

We relate the concept of multiscaling in the inertial range of turbulence to a hidden scaling symmetry. We deduce that the anomalous exponents of scaling laws are determined solely by the degree of time-scale homogeneity of the observed quantities. This yields a universal rule that includes the usual structure functions and Kolmogorov multipliers, and extends further to multi-time correlations and other multi-time properties of turbulent statistics.

[Phys. Rev. Fluids 10, 054603] Published Tue May 06, 2025

Author(s): Xin-Yang Liu, Meet Hemant Parikh, Xiantao Fan, Pan Du, Qing Wang, Yi-Fan Chen, and Jian-Xun Wang

Synthetic inflow turbulence generation is a critical bottleneck for high-fidelity, eddy-resolving simulations due to limitations in realism, generalizability, and computational cost. This study introduces CoNFiLD-inlet, a parametric inflow generator that couples conditional neural fields with latent diffusion models to synthesize high-fidelity inflow turbulence with Reynolds number (Re) awareness. Unlike autoregressive or deterministic methods, CoNFiLD-inlet enables mesh-independent, stochastic generation of temporally coherent velocity fields with generalization across unseen Re. Comprehensive validations in DNS and WMLES confirm robustness, scalability, and superior statistical fidelity.

[Phys. Rev. Fluids 10, 054901] Published Tue May 06, 2025

Author(s): Zhe Feng

This study investigates steady solutions of two-dimensional Rayleigh-Bénard convection under Navier-slip boundary conditions, bridging the gap between classical no-slip and free-slip models. By systematically varying the slip length, the work reveals a critical range where the heat transport and flow strength are highly sensitive to the boundary slip. The findings uncover universal scaling laws and highlight the pivotal role of slip length in modulating boundary layer structures and optimizing heat-flux configurations, offering new insights into both theoretical fluid dynamics and practical microstructured surface applications.

[Phys. Rev. Fluids 10, 053502] Published Mon May 05, 2025

Author(s): Weilin Chen, Huan Ping, Chunning Ji, Md. Mahbub Alam, and Yan Bao

This paper presents a systematic investigation of vortex-induced vibration (VIV) of a D-section prism at subcritical Re. It is found that the response is persistently VIV typed, which can be excited and sustained by the viscous and/or pressure lift coefficient. Galloping is found to be absent because it requires an unstable structural mode with a frequency close to the prism natural frequency and flow mode with the natural vortex shedding frequency.

[Phys. Rev. Fluids 10, 054102] Published Mon May 05, 2025

Author(s): Samantha A. McBride, Fernando Temprano-Coleto, Paul R. Kaneelil, Reese Knopp, Aubrey J. Taylor, Mariko A. Storey-Matsutani, Jessica L. Wilson, Mohammad Sadeq Saleh, Andrew R. Konicek, Arben Jusufi, Mohsen S. Yeganeh, and Howard A. Stone

Multiphase displacement is important in oil recovery, microfluidics, and CO2 capture. We study viscous oil trapping in microfluidic devices with sinusoidal pockets during water invasion. Varying capillary number (Ca), viscosity ratios, and pore geometries reveals that higher oil viscosity and water velocities increase oil trapping due to transition from meniscus displacement to viscous fingering. We find that trapping dynamics at high Ca are geometry independent. Our three-dimensional model based on the long-wave approximation predicts some experimental observations, such as increased oil retention at higher Ca and viscosity ratios, and the characteristic interfacial shape of trapped oil.

[Phys. Rev. Fluids 10, 054201] Published Mon May 05, 2025

Author(s): V. R. Krishna Priya, Snehal Sunil Patil, Somnath Roy, Konduri Aditya, and Rajaram Lakkaraju

Oceanic eddies are dynamic swirling formations that vary in size from about a few kilometers at mid-latitudes to hundreds of kilometers near the tropics. These eddies can persist for days to months and play a crucial role in regulating the climate by transporting heat, salt, and marine life over long distances. Through complex networks, we have discovered both local and nonlocal interactions between these eddies. We have also examined their connectivity and resilience to evaluate the ecosystem’s capacity to withstand disturbances.

[Phys. Rev. Fluids 10, 054402] Published Mon May 05, 2025

Author(s): Pranav Nath and Jean-Pierre Hickey

High-Reynolds number turbulence presents an enormous computational challenge due to its large scale separation. We explore a reduced dimensional approach to compute forced Homogeneous Isotropic Turbulence (HIT) up to a Taylor-scale Reynold’s number of 5428. The developed formulation based on one-dimensional turbulence captures many quantitative characteristics of HIT including energy spectra, normalized dissipation rate, skewness, energy flux, high-order structure functions and intermittency, along with an insight into occurrence of extreme events.

[Phys. Rev. Fluids 10, 054602] Published Mon May 05, 2025

Author(s): Rahul K. Singh

The dynamics of fibers, modeled as a sequence of inertial beads linked via elastic springs, in turbulent flows is dictated by a nontrivial interplay of inertia and elasticity. Such elastic, inertial fibers preferentially sample a three-dimensional turbulent flow in a manner that is qualitatively sim…

[Phys. Rev. E 111, L053101] Published Mon May 05, 2025

Author(s): Daigaku Katsumi, Masanobu Inubushi, and Naoto Yokoyama

Quasi-stable large-scale circulation in turbulent thermal convection intermittently reverses its rotational direction. A fusion of physical insight into turbulent convection and a data-driven method known as reservoir computing enables accurate prediction of these chaotic reversals using only non-intrusive sensing via measurements of shear stresses and temperatures on the sidewalls. The successful prediction using such non-intrusive and sparse sensing opens up possibilities for closed-loop control of turbulent flows and feasibility in industrial applications.

[Phys. Rev. Fluids 10, 053501] Published Fri May 02, 2025

Author(s): Tristan Gilet and Loïc Tadrist

During heavy rainstorms, how can pathogenic spores at the surface of plant leaves travel upward and contaminate other leaves above? The spores are released in the sessile drops left on the leaves by previous raindrops. In this manuscript, we show that upon impact of a large raindrop, a leaf may strongly vibrate. The subsequent inertial forces may be sufficient to expel water from its surface. We describe this droplet ejection mechanism as a function of both leaf and raindrop properties. The droplets inherit from the leaf velocity, so some of them can be shot upward. This ejection mechanism likely induces a significant upward flux of biological material during rainstorms.

[Phys. Rev. Fluids 10, 053601] Published Fri May 02, 2025

Author(s): Prateek Gupta and Satish Kumar

Motivated by the need to improve fundamental understanding of multilayer coating on discrete objects, we consider a model problem involving the flow of bilayer thin liquid films on rotating cylinders. A parametric study reveals that the critical rotation rate required to cause motion of liquid lobes that form due to gravitational drainage is lowered for a more viscous and thicker inner film due to an increase in viscous forces. These properties of the inner layer also lead to a reduction in the amplitude of temporal oscillations in the film thickness. In addition to advancing fundamental understanding, we suggest strategies for improving the uniformity of coatings on discrete objects.

[Phys. Rev. Fluids 10, 054001] Published Fri May 02, 2025

Author(s): Shruti Pandey and V. Shankar

The recently discovered polymer diffusive instability (PDI) in rectilinear flows of an Oldroyd-B fluid has wavelengths of the order of the size of the polymer for realistic polymer diffusivities, raising a question on the applicability of continuum constitutive equations. We show, using the Giesekus model (augmented with stress diffusion), that the PDI is rapidly suppressed as the anisotropy parameter is increased, suggesting that anisotropic diffusion needs to be incorporated in order to obtain physically consistent results, either in stability calculations or in direct numerical simulations.

[Phys. Rev. Fluids 10, 053301] Published Thu May 01, 2025

Author(s): Qiang Zhu and Qing Xiao

Most existing propulsion systems rely on pressure for thrust generation, with shear stress being a major source of drag associated with skin friction. In this study, we propose a novel thrust-generation system using shear stress for thrust production. It features a barrel-shaped body whose outer membrane circulates in a tank-treading manner. Through numerical simulations, the feasibility of this design has been confirmed. The underlying physics and the potential performance have also been explored.

[Phys. Rev. Fluids 10, 054101] Published Thu May 01, 2025

Author(s): Yanxuan Shao, Jean-Regis Angilella, and Adilson E. Motter

Microfluidic systems have traditionally relied on external hardware or compliant structures to generate flow rate oscillations. Here, we demonstrate that persistent oscillations and even chaotic behavior can spontaneously emerge without external modulation, deformable structures, or fluid compressibility. Through a combination of numerical simulations and a reduced model, we uncover a mechanism governed by fluid inertia that drives this behavior at moderate Reynolds numbers. These findings expand the design space for on-chip flow control and reveal new opportunities for microfluidic timing, precision control, and chaos-based applications.

[Phys. Rev. Fluids 10, 054401] Published Thu May 01, 2025

Author(s): Wandrille Ruffenach, Lucas Fery, and Bérengère Dubrulle

This study presents a simplified model for shear flows developed to capture essential features of turbulence using a sparse representation based on intense structures called vortons. These dynamically regularized quasi-singularities interact with large-scale shear and give rise to two distinct flow regimes: a laminar regime governed by large-scale dissipation and a turbulent regime driven by vorton activity. Remarkably, the model reproduces power-law scaling behaviors consistent with classical turbulence, offering a compact yet insightful tool for investigating energy transfer and dissipation in complex flows.

[Phys. Rev. Fluids 10, 054601] Published Thu May 01, 2025

Author(s): N. S. Satpathi, G. S. G. Reddy, and A. K. Sen

Controlling the behavior of impacting droplets continues to remain a challenge. We demonstrate a simple method of inclining a plane superhydrophobic surface with a sudden wettability change in the form of a superhydrophilic spot to control the droplet impact dynamics. We find that, depending on the …

[Phys. Rev. E 111, 055101] Published Thu May 01, 2025

Author(s): Raffaello Foldes, Raffaele Marino, Silvio Sergio Cerri, and Enrico Camporeale

We studied the feedback of extreme vertical velocity drafts on the dynamics of stratified turbulent flows using a coarse-graining approach. This approach allowed for a local-in-scale analysis while preserving spatial detail, which is critical for assessing energy transfer and conversion in large-scale intermittent flows of geophysical interest. We found that vertical drafts may act as a local energy injection mechanism throughout the flow domain, affecting the exchange between kinetic and potential energy.

[Phys. Rev. Fluids 10, 043803] Published Wed Apr 30, 2025

Author(s): Hui Zhao, Xiangchun Xuan, and Ning Wu

Theory and simulation are used to demonstrate that the concentration polarization induced electro-osmotic (CPEO) flow is the origin of the experimentally observed nonlinear electrokinetic flow near a charged dielectric corner. The CPEO explains many experimentally observed electrokinetic phenomena that cannot be captured by existing electrokinetic theories. The CPEO can become a versatile technique in the microfluidic toolbox and open many new possibilities to use dielectric structures for fluidic flow control.

[Phys. Rev. Fluids 10, 044203] Published Wed Apr 30, 2025

Author(s): Scott K. Hansen and Daniel O'Malley

We consider conditions for minimum energy dissipation and advective travel time along path lines for potential flows in heterogeneous porous and fractured media. The work employs some concepts and techniques not often seen in the literature on Darcy (and cubic law) flows, including M. King Hubbert’s energy-based conception and variational methods. We explain a seemingly surprising result concerning how travel time through a series of fracture segments responds to small, local aperture perturbations.

[Phys. Rev. Fluids 10, 043802] Published Mon Apr 28, 2025

Author(s): Mahdi Saeedipour and Simon Schneiderbauer

This study investigates the systematic connection between the statistics of non-decaying homogeneous isotropic turbulence and droplet fragmentation outcomes, based on the concept of the enstrophy transport equation. Analysis of the interface-resolved direct numerical simulations (DNS) underlines the role of different vorticity generation mechanisms, such as vortex stretching and surface tension, in determining the size of the largest stable droplet during turbulent fragmentation known as the Kolmogorov-Hinze scale. The findings serve as the basis for future theory development under more complex turbulent fragmentation conditions.

[Phys. Rev. Fluids 10, 044301] Published Mon Apr 28, 2025