arXiv - PHYS - Fluid Dynamics最新文献_第2页

On force balance in Brinkman fluids under confinement 布林克曼流体在约束条件下的力平衡

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-16 DOI: arxiv-2409.10183

Abdallah Daddi-Moussa-Ider, Andrej Vilfan

引用次数: 0

Sticking without contact: Elastohydrodynamic adhesion 无接触粘附：弹流粘附

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-16 DOI: arxiv-2409.10723

Vincent Bertin, Alexandros T. Oratis, Jacco H. Snoeijer

{"title":"Sticking without contact: Elastohydrodynamic adhesion","authors":"Vincent Bertin, Alexandros T. Oratis, Jacco H. Snoeijer","doi":"arxiv-2409.10723","DOIUrl":"https://doi.org/arxiv-2409.10723","url":null,"abstract":"The adhesion between dry solid surfaces is typically governed by contact\u0000forces, involving surface forces and elasticity. For surfaces immersed in a\u0000fluid, out-of-contact adhesion arises due to the viscous resistance to the\u0000opening of the liquid gap. While the adhesion between dry solids is described\u0000by the classical JKR theory, there is no equivalent framework for the wet\u0000adhesion of soft solids. Here, we investigate theoretically the viscous\u0000adhesion emerging during the separation of a sphere from an elastic substrate.\u0000The suction pressure within the thin viscous film between the solids induces\u0000significant elastic displacements. Unexpectedly, the elastic substrate closely\u0000follows the motion of the sphere, leading to a sticking without contact. The\u0000initial dynamics is described using similarity solutions, resulting in a\u0000nonlinear adhesion force that grows in time as F ~ t^(2/3). When elastic\u0000displacements become large enough, another similarity solution emerges that\u0000leads to a violent snap-off of the adhesive contact through a finite-time\u0000singularity. The observed phenomenology bears a strong resemblance with JKR\u0000theory, and is relevant for a wide range of applications involving viscous\u0000adhesion.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142267534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Spontaneous emission of internal waves by a radiative instability 辐射不稳定性自发产生的内波

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-16 DOI: arxiv-2409.10758

Subhajit Kar, Roy Barkan, James C. McWilliams, M. Jeroen Molemaker

{"title":"Spontaneous emission of internal waves by a radiative instability","authors":"Subhajit Kar, Roy Barkan, James C. McWilliams, M. Jeroen Molemaker","doi":"arxiv-2409.10758","DOIUrl":"https://doi.org/arxiv-2409.10758","url":null,"abstract":"The spontaneous emission of internal waves (IWs) from balanced mesoscale\u0000eddies has been previously proposed to provide a source of oceanic IW kinetic\u0000energy (KE). This study examines the mechanisms leading to the spontaneous\u0000emission of spiral-shaped IWs from an anticyclonic eddy with an order-one\u0000Rossby number, using a high-resolution numerical simulation of a flat-bottomed,\u0000wind-forced, reentrant channel flow configured to resemble the Antarctic\u0000Circumpolar Current. It is demonstrated that IWs are spontaneously generated as\u0000a result of a loss of balance process that is concentrated at the eddy edge,\u0000and then radiate radially outward. A 2D linear stability analysis of the eddy\u0000shows that the spontaneous emission arises from a radiative instability which\u0000involves an interaction between a vortex Rossby wave supported by the radial\u0000gradient of potential vorticity and an outgoing IWs. This particular\u0000instability occurs when the perturbation frequency is superinertial. This\u0000finding is supported by a KE analysis of the unstable modes and the numerical\u0000solution, where it is shown that the horizontal shear production provides the\u0000source of perturbation KE. Furthermore, the horizontal length scale and\u0000frequency of the most unstable mode from the stability analysis agree well with\u0000those of the spontaneously emitted IWs in the numerical solution.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142267530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Advancing flight physics through natural adaptation and animal learning 通过自然适应和动物学习推进飞行物理学的发展

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-16 DOI: arxiv-2409.10067

Ariane Gayout, David Lentink

引用次数: 0

uniGasFoam: a particle-based OpenFOAM solver for multiscale rarefied gas flows uniGasFoam：基于粒子的 OpenFOAM 多尺度稀薄气体流求解器

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-16 DOI: arxiv-2409.10288

Nikos Vasileiadis, Giorgos Tatsios, Craig White, Duncan A. Lockerby, Matthew K. Borg, Livio Gibelli

{"title":"uniGasFoam: a particle-based OpenFOAM solver for multiscale rarefied gas flows","authors":"Nikos Vasileiadis, Giorgos Tatsios, Craig White, Duncan A. Lockerby, Matthew K. Borg, Livio Gibelli","doi":"arxiv-2409.10288","DOIUrl":"https://doi.org/arxiv-2409.10288","url":null,"abstract":"This paper presents uniGasFoam, an open-source particle-based solver for\u0000multiscale rarefied gas flow simulations, which has been developed within the\u0000well-established OpenFOAM framework, and is an extension of the direct\u0000simulation Monte Carlo (DSMC) solver dsmcFoam+. The developed solver addresses\u0000the coupling challenges inherent in hybrid continuum-particle methods,\u0000originating from the disparate nature of finite-volume (FV) solvers found in\u0000computational fluid dynamics (CFD) software and DSMC particle solvers. This is\u0000achieved by employing alternative stochastic particle methods, resembling DSMC,\u0000to tackle the continuum limit. The uniGasFoam particle-particle coupling\u0000produces a numerical implementation that is simpler and more robust, faster in\u0000many steady-state flows, and more scalable for transient flows compared to\u0000conventional continuum-particle coupling. The presented framework is unified\u0000and generic, and can couple DSMC with stochastic particle (SP) and unified\u0000stochastic particle (USP) methods, or be employed for pure DSMC, SP, and USP\u0000gas simulations. To enhance user experience, optimise computational resources\u0000and minimise user error, advanced adaptive algorithms such as transient\u0000adaptive sub-cells, non-uniform cell weighting, and adaptive global time\u0000stepping have been integrated into uniGasFoam. In this paper, the hybrid\u0000USP-DSMC module of uniGasFoam is rigorously validated through multiple\u0000benchmark cases, consistently showing excellent agreement with pure DSMC,\u0000hybrid CFD-DSMC, and literature results. Notably, uniGasFoam achieves\u0000significant computational gains compared to pure dsmcFoam+ simulations,\u0000rendering it a robust computational tool well-suited for addressing multiscale\u0000rarefied gas flows of engineering importance.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142267535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Hydrodynamic mechanism for stable spindle positioning in meiosis II oocytes 减数分裂 II 卵母细胞中纺锤体稳定定位的水动力机制

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-16 DOI: arxiv-2409.10401

Weida Liao, Eric Lauga

{"title":"Hydrodynamic mechanism for stable spindle positioning in meiosis II oocytes","authors":"Weida Liao, Eric Lauga","doi":"arxiv-2409.10401","DOIUrl":"https://doi.org/arxiv-2409.10401","url":null,"abstract":"Cytoplasmic streaming, the persistent flow of fluid inside a cell, induces\u0000intracellular transport, which plays a key role in fundamental biological\u0000processes. In meiosis II mouse oocytes (developing egg cells) awaiting\u0000fertilisation, the spindle, which is the protein structure responsible for\u0000dividing genetic material in a cell, must maintain its position near the cell\u0000cortex (the thin actin network bound to the cell membrane) for many hours.\u0000However, the cytoplasmic streaming that accompanies this stable positioning\u0000would intuitively appear to destabilise the spindle position. Here, through a\u0000combination of numerical and analytical modelling, we reveal a new,\u0000hydrodynamic mechanism for stable spindle positioning beneath the cortical cap.\u0000We show that this stability depends critically on the spindle size and the\u0000active driving from the cortex, and demonstrate that stable spindle positioning\u0000can result purely from a hydrodynamic suction force exerted on the spindle by\u0000the cytoplasmic flow. Our findings show that local fluid dynamic forces can be\u0000sufficient to stabilise the spindle, explaining robustness against\u0000perturbations not only perpendicular but also parallel to the cortex. Our\u0000results shed light on the importance of cytoplasmic streaming in mammalian\u0000meiosis.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"52 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142267542","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Experimental Study on Boiling of Nanofluids in Copper Foam 纳米流体在铜泡沫中沸腾的实验研究

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-16 DOI: arxiv-2409.09995

Kai-Xin Hu, Jing-Han Pan

引用次数: 0

Large/small eddy simulations: A high-fidelity method for studying high-Reynolds number turbulent flows 大/小涡流模拟：研究高雷诺数湍流的高保真方法

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-15 DOI: arxiv-2409.09901

Arnab Moitro, Sai Sandeep Dammati, Alexei Y. Poludnenko

{"title":"Large/small eddy simulations: A high-fidelity method for studying high-Reynolds number turbulent flows","authors":"Arnab Moitro, Sai Sandeep Dammati, Alexei Y. Poludnenko","doi":"arxiv-2409.09901","DOIUrl":"https://doi.org/arxiv-2409.09901","url":null,"abstract":"Direct numerical simulations (DNS) are one of the main ab initio tools to\u0000study turbulent flows. However, due to their considerable computational cost,\u0000DNS are primarily restricted to canonical flows at moderate Reynolds numbers,\u0000in which turbulence is isolated from the realistic, large-scale flow dynamics.\u0000In contrast, lower fidelity techniques, such as large eddy simulations (LES),\u0000are employed for modelling real-life systems. Such approaches rely on closure\u0000models that make multiple assumptions, including turbulent equilibrium,\u0000small-scale universality, etc., which require prior knowledge of the flow and\u0000can be violated. We propose a method, which couples a lower-fidelity,\u0000unresolved, time-dependent calculation of an entire system (LES) with an\u0000embedded Small-Eddy Simulation (SES) that provides a high-fidelity, fully\u0000resolved solution in a sub-region of interest of the LES. Such coupling is\u0000achieved by continuous replacement of the large SES scales with a low-pass\u0000filtered LES velocity field. The method is formulated in physical space, makes\u0000no assumptions of equilibrium, small-scale structure, and boundary conditions.\u0000A priori tests of both steady and unsteady homogeneous, isotropic turbulence\u0000are used to demonstrate the method accuracy in recovering turbulence\u0000properties, including spectra, probability density functions of the\u0000intermittent quantities, and sub-grid dissipation. Finally, SES is compared\u0000with two alternative approaches: one embedding a high-resolution region through\u0000static mesh refinement and a generalization of the traditional volumetric\u0000spectral forcing. Unlike these methods, SES is shown to achieve DNS-level\u0000accuracy at a fraction of the cost of the full DNS, thus opening the\u0000possibility to study high-Re flows.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"103 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142267539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Periodic Steady Vortices in a Stagnation Point Flow II 停滞点流体中的周期性稳定漩涡 II

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-15 DOI: arxiv-2409.09695

Oliver S. Kerr

引用次数: 0

Giant superhydrophobic slip of shear-thinning liquids 剪切稀化液体的巨型超疏水性滑移

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-14 DOI: arxiv-2409.09374

Ory Schnitzer, Prasun K. Ray

引用次数: 0