Physical Review Fluids最新文献

{"title":"Steady streaming in channels with a porous interior.","authors":"Guillermo L Nozaleda, Javier Alaminos-Quesada, Cándido Gutiérrez-Montes, Antonio L Sánchez","doi":"10.1103/89kj-npfn","DOIUrl":"10.1103/89kj-npfn","url":null,"abstract":"<p><p>Hall, in his Ph.D. thesis (University of London, 1973), demonstrated that the viscous flow arising in a slender channel of slowly varying cross section subject to a purely oscillatory pressure difference between its open ends contains a steady streaming component. This study extends the analysis to channels with a porous interior. Using a homogenized flow model that incorporates a Darcy resistance term proportional to the local velocity, a closed-form solution for the streaming motion is derived in the asymptotic limit of small stroke-to-channel length ratios <math><mi>ε</mi> <mo>≪</mo> <mn>1</mn></math> . Consistent with Hall's findings, a net flow rate is seen to arise only when the channel ends have unequal widths. The presence of a porous medium significantly attenuates the streaming-flow magnitude, with the differences between porous and nonporous channels becoming more pronounced for large Womersley numbers, a limiting case considered separately. In nonporous channels with unequal end widths the streaming motion exhibits large velocities that are comparable in magnitude to those of the oscillatory flow, whereas in porous channels the streaming velocities remain a factor <math><mi>ε</mi></math> smaller. Channels with equal end widths feature streaming recirculating vortices within near-wall Stokes boundary layers. Nonporous channels display additional recirculating vortices in the central core region, which are absent in porous configurations. These results provide insights into transport processes in biomedical and technological applications involving oscillatory flow in wall-bounded porous media.</p>","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"10 9","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12768334/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145912573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CoNFiLD-inlet: Synthetic turbulence inflow using generative latent diffusion models with neural fields.","authors":"Xin-Yang Liu, Meet Hemant Parikh, Xiantao Fan, Pan Du, Qing Wang, Yi-Fan Chen, Jian-Xun Wang","doi":"10.1103/physrevfluids.10.054901","DOIUrl":"https://doi.org/10.1103/physrevfluids.10.054901","url":null,"abstract":"<p><p>Eddy-resolving turbulence simulations require stochastic inflow conditions that accurately replicate the complex, multiscale structures of turbulence. Traditional recycling-based methods rely on computationally expensive precursor simulations while existing synthetic inflow generators often fail to reproduce realistic coherent structures of turbulence. Recent advances in deep learning (DL) have opened new possibilities for inflow turbulence generation, yet many DL-based methods rely on deterministic, autoregressive frameworks prone to error accumulation, resulting in poor robustness for long-term predictions. In this work, we present CoNFiLD-inlet, a novel DL-based inflow turbulence generator that integrates diffusion models with a conditional neural field to produce realistic, stochastic inflow turbulence. By parametrizing inflow conditions using Reynolds numbers, CoNFiLD-inlet generalizes effectively across a wide range of Reynolds numbers ( <math> <msub><mrow><mtext>Re</mtext></mrow> <mrow><mi>τ</mi></mrow> </msub> </math> between 10³ and 10⁴) without requiring retraining or parameter tuning. Comprehensive validation through <i>a priori</i> and <i>a posteriori</i> tests in direct numerical simulation and wall-modeled large-eddy simulation demonstrates its high fidelity, robustness, and scalability, positioning it as an efficient and versatile solution for inflow turbulence synthesis.</p>","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"10 5","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13108683/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147778522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimal trajectories for Bayesian olfactory search in turbulent flows: The low information limit and beyond.","authors":"R A Heinonen, L Biferale, A Celani, M Vergassola","doi":"10.1103/physrevfluids.10.044601","DOIUrl":"https://doi.org/10.1103/physrevfluids.10.044601","url":null,"abstract":"<p><p>In turbulent flows, tracking the source of a passive scalar cue requires exploiting the limited information that can be gleaned from rare, randomized encounters with the cue. When crafting a search policy, the most challenging and important decision is what to do in the absence of an encounter. In this work, we perform high-fidelity direct numerical simulations of a turbulent flow with a stationary source of tracer particles, and obtain quasi-optimal policies (in the sense of minimal average search time) with respect to the empirical encounter statistics [1-3]. We study the trajectories under such policies and compare the results to those of the infotaxis heuristic. In the presence of a strong mean wind, the optimal motion in the absence of an encounter is zigzagging (akin to the well-known insect behavior \"casting\") followed by a return to the starting location. The zigzag motion generates characteristic <math> <mrow><msup><mi>t</mi> <mrow><mn>1</mn> <mo>/</mo> <mn>2</mn></mrow> </msup> </mrow> </math> scaling of the rms displacement envelope. By passing to the limit where the probability of detection vanishes, we connect these results to the classical linear search problem and derive an estimate of the tail of the arrival time pdf as a stretched exponential <math><mrow><mi>p</mi> <mo>(</mo> <mi>T</mi> <mo>)</mo> <mo>∼</mo> <mtext>exp</mtext> <mo>(</mo> <mo>-</mo> <mi>k</mi> <msqrt><mi>T</mi></msqrt> <mo>)</mo></mrow> </math> for some <math><mrow><mi>k</mi> <mo>></mo> <mn>0</mn></mrow> </math> , in agreement with Monte Carlo results. We also discuss what happens as the wind speed becomes smaller.</p>","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"10 4","pages":""},"PeriodicalIF":2.5,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12369886/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144965062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Laboratory study of wave turbulence under isotropic forcing","authors":"Z. Taebel, M. L. McAllister, A. Scotti, M. Onorato, T. S. van den Bremer","doi":"10.1103/physrevfluids.9.094803","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.094803","url":null,"abstract":"The statistical treatment of random weakly nonlinear interactions between waves, called wave turbulence (WT), is fundamental to understanding the development of the ocean surface. For gravity waves, wave turbulence predicts a dual (direct and inverse) cascade of energy and wave action, which yield power-law solutions for the energy spectrum. While energy cascades were predicted more than 50 years ago, observing them in the laboratory with mechanical forcing remains a challenge. Here, we present experiments in which we attempted to reproduce both direct and inverse cascades in a large circular wave tank. The geometry of the wave tank allows for the creation of isotropically spread surface waves, which is an assumption that underlies WT theory. Although we did see evidence of a direct cascade of energy, we did not observe an inverse cascade of wave action. We discuss the competing effects of dissipation and intermittency, which may dominate or obscure the weakly nonlinear dynamics.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"26 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142251968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cavitation caused by an elastic membrane deforming under the jetting of a spark-induced bubble","authors":"Yuxue Zhong, Jingzhu Wang, Jianlin Huang, Yiwei Wang","doi":"10.1103/physrevfluids.9.093604","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.093604","url":null,"abstract":"The collapse of a spark-induced bubble results in a high-speed jet, and when that jet impacts an elastic membrane, the latter deforms considerably and is accompanied by secondary cavitation. The cavitation bubble then moves away from the membrane with subsequent oscillation. To study the mechanism for this cavitation, experiments involving diffuse light and particle image velocimetry were conducted to capture the behaviors of the cavitation bubble and flow field resulting from the rapid deformation of the membrane. Analyzing the velocity and pressure fields reveals secondary cavitation induced by a sudden acceleration rather than a large velocity. Secondary cavitation occurs when the dimensionless inertial force overcomes the dimensionless pressure difference required for cavitation; subjecting these dimensionless quantities to a parametric study shows that the secondary cavitation occurs when the former is greater than the latter. During the collapse of the cavitation bubble, a thin jet points toward the membrane with an impact velocity of approximately 35 m/s. The subsequent oscillation of the cavitation bubble results in vortex flow moving away from the membrane. These findings provide insights into engineering applications such as bioengineering and mixing.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"5 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142251967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Waves beneath a drop levitating over a moving wall","authors":"Kyle I. McKee, Bauyrzhan K. Primkulov, Kotaro Hashimoto, Yoshiyuki Tagawa, John W. M. Bush","doi":"10.1103/physrevfluids.9.093603","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.093603","url":null,"abstract":"In recent experiments, [E. Sawaguchi <i>et al.</i>, <span>J. Fluid Mech.</span> <b>862</b>, 261 (2019)] directly probed the lubrication layer of air beneath a droplet levitating inside a rotating cylindrical drum. For small rotation rates of the drum, the lubrication film beneath the drop adopted a steady shape, while at higher rotation rates, traveling waves propagated along the drop's lower surface with roughly half the wall velocity. Here, we rationalize the physical origin of these waves. We begin with a simplified model of the lubrication flow beneath the droplet, and examine the linear stability of this base state to perturbations of the Tollmien-Schlichting type. Our developments lead to the Orr-Sommerfeld equation (OSE), whose eigenvalues give the growth rates and phase speeds of the perturbations. By considering wavelengths long relative to the lubrication film thickness, we solve the OSE perturbatively and so deduce the wavelength and phase velocity of the most unstable mode. We find satisfactory agreement between experiment and theory over the parameter regime considered in the laboratory.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"36 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142268723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Drainage-induced spontaneous film climbing in capillaries","authors":"P. Pirdavari, H. Tran, Z. He, M. Y. Pack","doi":"10.1103/physrevfluids.9.094005","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.094005","url":null,"abstract":"This study reports the ability with which surface tension gradients are formed plainly by the drainage in a capillary containing a surfactant-laden liquid slug initially held in place by a vacuum. Provided that a thin film forms on the walls transverse to the downward flow, the drainage induces a surfactant gradient (i.e., Marangoni effect), which then leads to a film-climbing event against gravity. The overall climbing effect is limited by the capillary rise height (i.e., propensity for infiltration due to surface tension) and the surfactant gradient formed postmeniscus drainage, thus revealing a twofold role of surface tension in gravity-oriented capillaries hitherto unexplored. The interplay of mechanisms influencing the climbing films include surfactant kinetics, diffusion, and advection of surfactants.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"65 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142251970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Viscosity of capsule suspensions: Effects of internal-external viscosity ratio and capsule rupture release","authors":"Huiyong Feng, Haibo Huang, Jian Hou, Chao Li, Bei Wei","doi":"10.1103/physrevfluids.9.093602","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.093602","url":null,"abstract":"This work explores the variation of viscosity of capsule suspension during the process of capsule rupture and polymer release using the immersed-boundary lattice Boltzmann method. The variation of viscosity is classified into three stages in the rupture process: the deformation stage, the rupture stage, and the stable stage. In the process of polymer release, two new stages of the variation of viscosity emerge: the diffusion stage and the dilution stage. Furthermore, the influence of viscosity ratio (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>λ</mi></math>) on the viscosity is investigated. We find that the effective viscosity grows with <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>λ</mi></math> and approaches the solid particle limit for very large <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>λ</mi></math>, reflecting a similar behavior in the capsule shape. Finally, an available law that relates suspension viscosity to <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>λ</mi></math>, capillary number (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>Ca</mi></math>), and volume fraction (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>ϕ</mi></math>) is established. The findings of this research have potential applications in fields such as oil exploration and capsule transportation.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"7 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142251969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Examination of the onset and decay of turbulence in pipe flow","authors":"Basheer A. Khan, Shai Arogeti, Alexander Yakhot","doi":"10.1103/physrevfluids.9.093903","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.093903","url":null,"abstract":"The crisis (or critical) Reynolds number (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mtext>Re</mtext><mi>c</mi></msub></math>) is established at 1870, describing the threshold beyond which the lifetimes of turbulent puffs prior to the relaminarization extend from <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>O</mi><mrow><mo>(</mo><msup><mn>10</mn><mn>4</mn></msup><mo>)</mo></mrow><mspace width=\"0.16em\"></mspace><mtext>to</mtext><mspace width=\"0.16em\"></mspace><mi>O</mi><mrow><mo>(</mo><msup><mn>10</mn><mn>6</mn></msup><mo>)</mo></mrow></mrow></math> time units (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>D</mi><mo>/</mo><msub><mi>U</mi><mi>m</mi></msub></mrow></math>), where <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>D</mi></math> and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>U</mi><mi>m</mi></msub></math> denote the pipe diameter and mean velocity, respectively. To analyze the role of inplane motion for sustaining turbulence, fully resolved direct numerical simulations have been performed to generate a localized, equilibrium turbulent puff at <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mtext>Re</mtext><mo>=</mo><mn>1920</mn></mrow></math>. Employing our approach based on proper orthogonal decomposition, the research confirms that azimuthal motion significantly contributes to the transition to turbulence. Notably, at supercritical Reynolds numbers (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mtext>Re</mtext><mo>&gt;</mo><msub><mtext>Re</mtext><mi>c</mi></msub></mrow></math>) ranging from <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mtext>Re</mtext><mo>=</mo><mn>1920</mn></mrow></math> to <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mtext>Re</mtext><mo>=</mo><mn>2100</mn></mrow></math>, reducing azimuthal motion energy by 80% substantially shortens the lifetime of turbulent puffs. It has been shown that the relaminarization of turbulent puffs at subcritical Reynolds numbers, <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mtext>Re</mtext><mo>=</mo><mn>1720</mn><mtext>–</mtext><mn>1840</mn></mrow></math>, clearly implies an exponential time decay of turbulence energy. The expression for the decay rate was obtained as a best-fit curve of direct numerical simulations.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"14 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142268450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Coupled volume of fluid and phase field method for direct numerical simulation of insoluble surfactant-laden interfacial flows and application to rising bubbles","authors":"Palas Kumar Farsoiya, Stéphane Popinet, Howard A. Stone, Luc Deike","doi":"10.1103/physrevfluids.9.094004","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.094004","url":null,"abstract":"Improved numerical methods are needed to understand the effect of surfactants in interfacial fluid mechanics, with various applications including thin films, inkjet printing, and ocean-atmosphere interactions. We provide a three-dimensional coupled volume of fluid (VoF) and phase field numerical approach to simulate the effects of insoluble surfactant-laden flows. The framework is validated against analytical cases for surfactant transport and Marangoni stresses. We then systematically investigate a single surfactant-laden rising bubble. The characteristics of a clean bubble rising in a quiescent liquid are governed by nondimensional numbers, i.e., the Galileo number <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mtext>Ga</mtext></math>, which compares inertial and viscous effects, and the Bond number <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mtext>Bo</mtext></math>, which compares gravitational and surface tension stresses. The effect of insoluble surfactants introduces an additional independent parameter, the Marangoni number <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mtext>Ma</mtext></math>, comparing the change in surface tension forces due to gradients in surfactants concentration with viscous forces. We apply our numerical methods to investigate the influence of surfactants (through the Marangoni number) on rising bubbles in otherwise quiescent fluids. We observe that an increase in the Marangoni number first decreases the rise velocity before reaching a limiting value at high <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mtext>Ma</mtext></math>. The value of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mtext>Ma</mtext></math> necessary to observe a significant slowdown increases with <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mtext>Ga</mtext></math>. We discuss the associated surfactant accumulation and the vortical dynamics when a steady state is reached. Finally, we perform three-dimensional simulations and demonstrate that Marangoni effects can induce a change in the rise trajectory from spiraling to zigzagging for set values of Bo and Ga, consistent with experimental results.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"32 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142227825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}