Latest papers in fluid mechanics

Shell models on recurrent sequences: Fibonacci, Padovan, and other series

Physical Review E - Fri, 02/14/2025 - 10:00

Author(s): L. Manfredini and Ö. D. Gürcan

A class of shell models is proposed where the shell variables are defined on a recurrent sequence of integer wave numbers such as the Fibonacci or the Padovan series or their variations, including a sequence made of square roots of Fibonacci numbers rounded to the nearest integer. Considering the si…


[Phys. Rev. E 111, 025103] Published Fri Feb 14, 2025

Numerical investigation of acoustic radiation force and microstreaming in a viscoelastic fluid

Physical Review E - Thu, 02/13/2025 - 10:00

Author(s): Khemraj Gautam Kshetri, Andrew Cook, and Nitesh Nama

We present a numerical model to study time-averaged acoustic radiation force and microstreaming around an elastic sphere immersed within an acoustically actuated viscoelastic fluid. We employ a perturbation approach to systematically identify limiting regimes where the viscoelastic fluid can be appr…


[Phys. Rev. E 111, 025102] Published Thu Feb 13, 2025

Stochastic model for the turbulent ocean heat flux under Arctic sea ice

Physical Review E - Wed, 02/12/2025 - 10:00

Author(s): S. Toppaladoddi and A. J. Wells

Arctic sea ice is one of the most sensitive components of the Earth’s climate system, and it is difficult to predict its evolution because of challenges in modeling the effects of the underlying ocean. The authors develop a simplified stochastic model for the turbulent heat flux from the ocean to the ice that shows good agreement with observational data.


[Phys. Rev. E 111, 025101] Published Wed Feb 12, 2025

Surge-protected mechanical amplifier of ion transport devised using a bipolar nanopore with broken symmetry

Physical Review E - Fri, 02/07/2025 - 10:00

Author(s): Arghyadeep Paul and N. R. Aluru

Electrokinetic ion transport under coupled external electric field and pressure drops has recently exhibited giant, but monotonous, mechanical amplifications of ionic current in some nanochannels. While such effects can be exploited to develop novel pressure-sensitive ionic circuits, they can also y…


[Phys. Rev. E 111, L023101] Published Fri Feb 07, 2025

Josephson-Anderson relation as diagnostic of turbulent drag reduction by polymers

Physical Review E - Fri, 01/24/2025 - 10:00

Author(s): Samvit Kumar, Simon Toedtli, Tamer A. Zaki, and Gregory L. Eyink

The detailed Josephson-Anderson relation, which equates instantaneously the volume-integrated vorticity flux and the work by pressure drop, has been the key to drag reduction in superconductors and superfluids. We employ a classical version of this relation to investigate the dynamics of polymer dra…


[Phys. Rev. E 111, 015105] Published Fri Jan 24, 2025

Effect of frequency-dependent shear and volume viscosities on molecular friction in liquids

Physical Review E - Thu, 01/23/2025 - 10:00

Author(s): Henrik Kiefer, Domenico Vitali, Benjamin A. Dalton, Laura Scalfi, and Roland R. Netz

The relation between the frequency-dependent friction of a molecule in a liquid and the hydrodynamic properties of the liquid is fundamental for molecular dynamics. We investigate this connection for a water molecule moving in liquid water using all-atomistic molecular dynamics (MD) simulations and …


[Phys. Rev. E 111, 015104] Published Thu Jan 23, 2025

Enhanced aluminum combustion within supercritical water induced by underwater electrical explosion

Physical Review E - Wed, 01/22/2025 - 10:00

Author(s): S. S. Liu, Y. B. Sun, C. Wang, J. K. Shao, and J. J. Tao

In this Letter, we report on the induction of aluminum combustion within supercritical water, facilitated by an underwater explosion bubble. This bubble, initiated using an aluminum-wire electrical discharge in a water-filled tank, typically spans tens of centimeters and undergoes oscillatory dynami…


[Phys. Rev. E 111, L013101] Published Wed Jan 22, 2025

Tumbling elimination induced by permeability: An experimental approach

Physical Review Fluids - Tue, 01/21/2025 - 10:00

Author(s): J. Sánchez-Rodríguez and F. Gallaire

Archetypal falling behaviors of impervious objects are classified into four modes: fluttering, tumbling, steady descent, and chaotic motion. We present in this paper an experimental result of stability induced by porosity and permeability. We discover that by drilling different porosity patterns, we can avoid tumbling and chaotic behavior in plates that, due to their inertia and Reynolds values, should tumble while falling according to the regime diagram of impervious plates. Instead, the majority of the plates flutter and a few even descend steadily.


[Phys. Rev. Fluids 10, 013904] Published Tue Jan 21, 2025

Linear model for secondary motions in stratified flows

Physical Review Fluids - Tue, 01/21/2025 - 10:00

Author(s): Abdelhalim Abdeldayem, Thijs Bon, Raúl Bayoán Cal, and Johan Meyers

The valley-mountain arrangement excites secondary vortices when interacting with the atmospheric boundary layer. In this paper we develop an analytical model to predict these secondary vortices in the case of thermal stratification. The model was compared to recent direct numerical simulations available in the literature which studied secondary motions in channel flow for a wide range of Reynolds and Richardson numbers. The model showed robust performance for the range of cases considered, showing error less than 5% for the temperature and below 20% for velocity in most cases.


[Phys. Rev. Fluids 10, 014605] Published Tue Jan 21, 2025

Numerical study of microorganisms swimming near a convex wall in a Giesekus fluid

Physical Review E - Tue, 01/21/2025 - 10:00

Author(s): Chenlin Zhu, Fangyuan Peng, Dingyi Pan, Zhaosheng Yu, and Zhaowu Lin

The motion of microorganisms in complex fluids stands out as a prominent subject within fluid mechanics. In our study, we utilize the fictitious domain method to investigate the locomotion of squirmers along a convex wall in Giesekus viscoelastic fluids. This study examines the influence of fluid el…


[Phys. Rev. E 111, 015103] Published Tue Jan 21, 2025

Transition time of a bouncing drop

Physical Review Fluids - Thu, 01/16/2025 - 10:00

Author(s): Yahua Liu, Seyed Ali Hosseini, Cong Liu, Milo Feinberg, Benedikt Dorschner, Zuankai Wang, and Ilya Karlin

Drops impacting superhydrophobic surfaces have a rim-lamella structure at maximum spreading. The volume ratio of these two components is shown to be Weber-independent and related to a new Weber-independent characteristic time, the transition time. Volume ratios from experiments and simulations at different Ohnesorge numbers are shown.


[Phys. Rev. Fluids 10, 013602] Published Thu Jan 16, 2025

Anisotropic growth dynamics of liquid bridge during droplet coalescence under acoustic levitation

Physical Review Fluids - Thu, 01/16/2025 - 10:00

Author(s): Hongyue Chen, Xianyu Nong, Bokun Zhao, Wenxuan Zhong, Kangqi Liu, Zhen Chen, and Duyang Zang

Coalescence of droplets is connected to fascinating interfacial fluid dynamics that is of great importance in a variety of natural and engineering systems. We here explore the growth dynamics of liquid bridges during droplet coalescence under acoustic levitation. We show that the early-time evolution of the liquid bridge follows a scaling law d∼t5 in the inertial regime, with different prefactors for horizontal and vertical growth. We also highlight the interplay between acoustic radiation pressure and Laplace pressures. A new dimensionless parameter, the Acoustic-Capillary Dynamics Number, is introduced to enhance our understanding of liquid bridge dynamics in acoustic fields.


[Phys. Rev. Fluids 10, 013603] Published Thu Jan 16, 2025

Continuous data assimilation closure for modeling statistically steady turbulence in large-eddy simulation

Physical Review Fluids - Thu, 01/16/2025 - 10:00

Author(s): Sagy R. Ephrati, Arnout Franken, Erwin Luesink, Paolo Cifani, and Bernard J. Geurts

We use a continuous data assimilation approach to obtain low-cost stand-alone computational models for fluid flows. A nudging method is used to enforce global flow statistics, yielding a data-driven stochastic model that obtains accurate flow representations at coarse grids at severely reduced computational costs. This is demonstrated for the two-dimensional Navier-Stokes equations and the quasi-geostrophic equations.


[Phys. Rev. Fluids 10, 013801] Published Thu Jan 16, 2025

Interaction of freestream turbulence and surface roughness in separation-induced transition

Physical Review Fluids - Thu, 01/16/2025 - 10:00

Author(s): Haocheng Wu, Yang Xiang, Gaohua Li, and Zifei Yin

This study explores how distributed surface roughness influences separation-induced transition on a flat plate, under the influence of freestream turbulence and adverse pressure gradients. Using direct numerical simulations, the interactions between freestream perturbations and vortices generated by roughness elements are investigated. Results reveal that low roughness accelerates instability development without dominating the transition process, while higher roughness causes a more intensified vortex mixing process and directly results in transition to turbulence.


[Phys. Rev. Fluids 10, 013903] Published Thu Jan 16, 2025

Wake interference effects on flapping dynamics of elastic inverted foil

Physical Review Fluids - Thu, 01/16/2025 - 10:00

Author(s): Aarshana R. Parekh and Rajeev K. Jaiman

This study examines how the unsteady wake from an upstream stationary cylinder impacts the flapping response of an elastic inverted foil. Through high-fidelity simulations, we identify a critical nondimensional bending rigidity above which wake interference effects result in distinct flapping dynamics governed by stiffness and mass ratio. Additionally, we propose a nondimensional parameter that captures the interplay between inertia and elasticity, offering insights into fluid-structure interactions with implications for renewable energy harvesting systems.


[Phys. Rev. Fluids 10, 014702] Published Thu Jan 16, 2025

Lack of self-similarity in transverse velocity increments and circulation statistics in two-dimensional turbulence

Physical Review Fluids - Thu, 01/16/2025 - 10:00

Author(s): Nicolás P. Müller and Giorgio Krstulovic

This numerical study on two-dimensional (2D) turbulence reveals that transverse structure functions in the inverse energy cascade display anomalous scaling properties, differing from the self-similar behavior of longitudinal ones. Using direct numerical simulations of incompressible Navier-Stokes equations, this study shows a link between the scaling exponents of transverse structure functions and velocity circulation moments. These findings provide new insights into the dynamics of 2D turbulence, with implications for understanding geophysical flows.


[Phys. Rev. Fluids 10, L012601] Published Thu Jan 16, 2025

Self-organization in a stably stratified, valley-shaped enclosure heated from below

Physical Review Fluids - Mon, 01/13/2025 - 10:00

Author(s): Patrick J. Stofanak, Cheng-Nian Xiao, and Inanc Senocak

Heating a stratified fluid in a valley-shaped container triggers a self-organizing flow. Starting from a quiescent state, any infinitesimal disturbance leads the flow through a transient three-dimensional phase before settling into a two-dimensional steady state. This complex pathway arises from the dominance of viscous dissipation over buoyant production. The orderly transition between 3D and 2D, supported by linear theory, sets our findings apart from transient chaos. While the final pattern is not predicted by linear theory, several stages align well with it. Our example offers new insights into self-organization in fluid systems with geophysical and astrophysical implications.


[Phys. Rev. Fluids 10, 014402] Published Mon Jan 13, 2025

Impact of intergranular bonds on morphology transition of two-phase fluid-induced deformation

Physical Review Fluids - Fri, 01/10/2025 - 10:00

Author(s): Feihu Ke, Chung-Yee Kwok, and Kang Duan

We conduct experimental and theoretical investigations into the previously unexplored effects of intergranular bonds within cohesive granular skeletons on multiphase flow dynamics. We illuminate that fluid forces can become large enough to surpass bond strength, leading to bond breakage and fracture initiation as capillary numbers increase. A first-ever phase diagram of five distinct fluid-fluid-grain displacement morphologies is established under varying flow and cohesion conditions. Through dimensional analysis, we propose a fracturing number Nf* = 1 as a theoretical threshold to characterize the onset of fluid-induced fracturing in cohesive media.


[Phys. Rev. Fluids 10, 013902] Published Fri Jan 10, 2025

Influence of stratified shear instabilities on particle sedimentation in three-dimensional simulations with application to marine carbon dioxide removal

Physical Review Fluids - Fri, 01/10/2025 - 10:00

Author(s): Adam J. K. Yang, Mary-Louise Timmermans, Jason Olsthoorn, and Alexis K. Kaminski

Stratified flow instabilities play a critical role in particle sedimentation in marine environments, influencing the efficacy of marine carbon dioxide removal strategies. Using direct numerical simulations, we reveal how these instabilities enhance or inhibit settling across flow regimes. Our findings highlight the dynamic interplay between turbulence, stratification, and particle dynamics, providing new insights into optimizing carbon removal techniques.


[Phys. Rev. Fluids 10, 014501] Published Fri Jan 10, 2025

Artificial-neural-network-based subgrid-scale models in the strain-rate eigenframe for large-eddy simulation of compressible turbulent channel flow

Physical Review Fluids - Fri, 01/10/2025 - 10:00

Author(s): Xingsi Ren, Dehao Xu, Jianchun Wang, and Shiyi Chen

Artificial-neural-network-based (ANN-based) subgrid-scale (SGS) models for turbulent channel flow often suffer from instability and poor generalization. Here, we propose an ANN-SGS model based on the strain-rate eigenframe and apply it to large eddy simulations of compressible turbulent channel flow. Our results indicate that the newly proposed model can predict flow statistics more accurately than traditional SGS models, and it also exhibits generalization capability for both Reynolds and Mach numbers.


[Phys. Rev. Fluids 10, 014603] Published Fri Jan 10, 2025

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