Physical Review Fluids最新文献

{"title":"Curvature-driven transport of thin Bingham fluid layers in airway bifurcations","authors":"Cyril Karamaoun, Haribalan Kumar, Médéric Argentina, Didier Clamond, Benjamin Mauroy","doi":"10.1103/physrevfluids.9.l081101","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.l081101","url":null,"abstract":"The mucus on the bronchial wall forms a thin layer of non-Newtonian fluid, protecting the lungs by capturing inhaled pollutants. Due to the corrugation of its interface with air, this layer is subject to surface tension forces that affect its rheology. This physical system is analyzed using lubrication theory and three-dimensional simulations. We characterize the nonlinear behavior of the mucus and show that surface tension effects can displace overly thick mucus layers in airway bifurcations. This movement can disrupt the mucociliary clearance and break the homogeneity of the layer thickness.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"37 3 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141936216","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":"Approximate derivation of the power law for the mean streamwise velocity in a turbulent boundary layer under zero-pressure gradient","authors":"J. Dey","doi":"10.1103/physrevfluids.9.084601","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.084601","url":null,"abstract":"Distribution of the mean streamwise velocity in a turbulent boundary layer over a flat plate can be represented by the equation <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>U</mi><mo>∼</mo><msup><mi>η</mi><mrow><mn>1</mn><mo>/</mo><mi>n</mi></mrow></msup></mrow></math>, as was widely used in the past; <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>U</mi></math> and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>η</mi></math> are the normalized velocity and the wall-normal distance, respectively. However, this <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>1</mn><mo>/</mo><mi>n</mi></mrow><mi mathvariant=\"normal\">th</mi></math>-power law is an empirical one. By incorporating either the Reynolds shear stress model of Wei <i>et al.</i> [<span>J. Fluid Mech.</span> <b>969</b>, A3 (2023)], which is in terms of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>U</mi></math> and the (normalized) wall-normal velocity (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>V</mi></math>), or a similar one in the boundary layer equations, it is found that <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>U</mi></math> and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>V</mi></math> are related as <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><msup><mi>U</mi><mrow><mo>(</mo><mi>H</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow></msup><mo>∼</mo><mspace width=\"4pt\"></mspace><msup><mi>V</mi><mrow><mo>(</mo><mi>H</mi><mo>−</mo><mn>1</mn><mo>)</mo></mrow></msup></mrow></math> in the outer region of a flat plate boundary layer; <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>H</mi></mrow></math> is the flow shape parameter. Along with the distribution of the wall-normal velocity (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>V</mi><mi>w</mi></msub></math>) of Wei <i>et al.</i>, the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>1</mn><mo>/</mo><mi>n</mi></mrow><mi mathvariant=\"normal\">th</mi></math>-power law for <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>U</mi></math> is obtained by equating the derivative (with respect to <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>η</mi></math>) of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>V</mi></math> with that of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>V</mi><mi>w</mi></msub></math>. Thus, this empirical power law seems to have a reasonable theoretical basis embedded in it.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"22 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141936219","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":"Biophysical fluid dynamics in a Petri dish","authors":"George T. Fortune, Eric Lauga, Raymond E. Goldstein","doi":"10.1103/physrevfluids.9.083101","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.083101","url":null,"abstract":"The humble Petri dish is perhaps the simplest setting in which to examine the locomotion of swimming organisms, particularly those whose body size is tens of microns to millimeters. The fluid layer in such a container has a bottom no-slip surface and a stress-free upper boundary. It is of fundamental interest to understand the flow fields produced by the elementary and composite singularities of Stokes flow in this geometry. Building on the few particular cases that have previously been considered in the literature, we study here the image systems for the primary singularities of Stokes flow subject to such boundary conditions—the Stokeslet, rotlet, source, rotlet dipole, source dipole, and stresslet—paying particular attention to the far-field behavior. In several key situations, the depth-averaged fluid flow is accurately captured by the solution of an associated Brinkman equation whose screening length is proportional to the depth of the fluid layer. The case of hydrodynamic bound states formed by spinning microswimmers near a no-slip surface, discovered first using the alga <i>Volvox</i>, is reconsidered in the geometry of a Petri dish, where the power-law attractive interaction between microswimmers acquires unusual exponentially screened oscillations.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"30 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141936144","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":"Improved two-temperature model with correction of non-Boltzmann effect for oxygen and nitrogen","authors":"Rui Xiong, Yufeng Han, Wei Cao","doi":"10.1103/physrevfluids.9.083201","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.083201","url":null,"abstract":"In thermochemical nonequilibrium processes, both the nonequilibrium between different kinds of internal energy of molecules and the non-Boltzmann (NB) energy state distribution significantly impact the dissociation rate coefficients. The conventional two-temperature (2-T) model fails to accurately portray these effects, especially the NB effect. Consequently, dissociation rate coefficients calculated by the 2-T model are inaccurate in simulating strong thermochemical nonequilibrium flow, resulting in a surface heat flux inconsistent with experimental data. This article investigates the influencing factor of the NB effect on the dissociation rate coefficient using the state-to-state (STS) method during the zero-dimensional heating process of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi mathvariant=\"normal\">N</mi><mn>2</mn></msub></math> and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi mathvariant=\"normal\">O</mi><mn>2</mn></msub></math>. Based on this, we develop a fitting formula to precisely correct the NB effect. Furthermore, we propose an improved model by integrating this fitting formula with the single-group linear maximum entropy model, which considers only the effect of nonequilibrium between different kinds of internal energy. This improved model provides an accurate description of thermochemical nonequilibrium on the dissociation rate coefficients. To validate the effectiveness of the improved model, we simulate the nonequilibrium process following a normal shock. The results demonstrate that in strong thermochemical nonequilibrium flow, compared to the 2-T Park model, the maximum and average discrepancies between the translation temperatures calculated by the improved model and those by the STS method are reduced by more than 68% and 82%, respectively. Additionally, the results closely align with experimental data, indicating that the improved model can accurately depict the effect of thermal nonequilibrium on dissociation rate coefficients.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"3 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141936220","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":"Sensitivity study of resolution and convergence requirements for the extended overlap region in wall-bounded turbulence","authors":"Sergio Hoyas, Ricardo Vinuesa, Peter Schmid, Hassan Nagib","doi":"10.1103/physrevfluids.9.l082601","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.l082601","url":null,"abstract":"Direct numerical simulations (DNSs) are among the most powerful tools for studying turbulent flows. Even though the achievable Reynolds numbers are lower than those obtained through experimental means, DNS offers a clear advantage: The entire velocity field is known, allowing for the evaluation of any desired quantity. This capability includes the computation of derivatives of all relevant terms. One such derivative provides the indicator function, which is the product of the wall distance and the wall-normal derivative of the mean streamwise velocity. This derivative may depend on mesh spacing and distribution, but it is extremely affected by the convergence of the simulation. The indicator function is crucial for understanding inner and outer interactions in wall-bounded flows and describing the overlap region between them. We find a clear dependence of this indicator function on the mesh distributions we examine, raising questions about classical mesh and convergence requirements for DNS and achievable accuracy. Within the framework of the logarithmic plus linear overlap region, coupled with a parametric study of channel flows and some pipe flows, sensitivities of extracted overlap parameters are examined. This study reveals a path to establishing their high-<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mtext>Re</mtext><mi>τ</mi></msub></math> or nearly asymptotic values at modest Reynolds numbers, but larger than the ones used in this work, accessible by high-quality DNS with reasonable cost.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"26 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141936221","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":"Retention or repulsion forces induced by bubbles trapped at the base of an immersed microparticle on a substrate","authors":"Anna Ipatova, Alexis Duchesne, H. N. Yoshikawa, Pascal Mariot, Corenthin Leroy, Christine Faille, Ichiro Ueno, Georg F. Dietze, Farzam Zoueshtiagh","doi":"10.1103/physrevfluids.9.084301","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.084301","url":null,"abstract":"We explore the potential for air bubble entrapment beneath micrometer-sized particles following immersion. This investigation employs theoretical, numerical, and experimental methodologies, with a focus on the wetting characteristics of both the particle and its substrate. These properties are crucial in determining the likelihood of entrapment and its impact on the particle's adhesion force to the substrate. The theoretical model provides the mathematical framework to account for the additional force exerted on the particle due to the entrapped bubble, while numerical calculations yield corresponding force values. The results underscore the significant influence of the wettability of both the particle and the substrate on this force. In support of findings of the numerical model, companion experiments were performed. The results demonstrate that the bubbles can indeed be entrapped at microscales underneath micrometric particles. Experimental measurements of detachment force reveal the substantial impact of these entrapped bubbles on the force required to detach particles from a surface. Specifically, the force appears notably higher when either the particle or the substrate, or both, exhibit hydrophobic characteristics. We highlight the alignment observed between numerical calculations and experimental results, while also examining and discussing any identified disparities and their root causes. Lastly, we propose an energy model that predicts the post-detachment configuration of the bubble, determining whether it remains attached to the particle, adheres to the substrate, or splits into daughter bubbles distributed across both surfaces. These findings hold significance for a wide range of industrial applications where the immersion of micrometer-sized entities, such as dirt or bacteria, is common during liquid-based cleaning processes.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"23 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883702","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":"Attached and separated rotating flow over a finite height ridge","authors":"S. Frei, E. Burman, E. Johnson","doi":"10.1103/physrevfluids.9.084801","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.084801","url":null,"abstract":"This article discusses the effect of rotation on the boundary layer in high Reynolds number flow over a ridge using a numerical method based on stabilized finite elements that captures steady solutions up to a Reynolds number of order <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mn>10</mn><mn>6</mn></msup></math>. The results are validated against boundary layer computations in shallow flows and for deep flows against experimental observations reported in Machicoane <i>et al.</i> [<span>Phys. Rev. Fluids</span> <b>3</b>, 034801 (2018)]. In all cases considered the boundary layer remains attached, even at arbitrarily large Reynolds numbers, provided the Rossby number of the flow is less than some critical Rossby number of order unity. At any fixed Rossby number larger than this critical value, the flow detaches at sufficiently high Reynolds number to form a steady recirculating region in the lee of the ridge. At even higher Reynolds numbers no steady flow is found. This disappearance of steady solutions closely reproduces the transition to unsteadiness seen in the laboratory.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"20 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883703","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":"Transient growth in diabatic boundary layers with fluids at supercritical pressure","authors":"Pietro Carlo Boldini, Benjamin Bugeat, Jurriaan W. R. Peeters, Markus Kloker, Rene Pecnik","doi":"10.1103/physrevfluids.9.083901","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.083901","url":null,"abstract":"In the region close to the thermodynamic critical point and in the proximity of the pseudoboiling (Widom) line, strong property variations substantially alter the growth of modal instabilities, as revealed in Ren <i>et al.</i> [<span>J. Fluid Mech.</span> <b>871</b>, 831 (2019)]. Here, we study nonmodal disturbances in the spatial framework using an eigenvector decomposition of the linearized Navier-Stokes equations under the assumption of locally parallel flow. To account for nonideality, a new energy norm is derived. Several heat transfer scenarios at supercritical pressure are investigated, which are of practical relevance in technical applications. The boundary layers with the fluid at supercritical pressure are heated or cooled by prescribing the wall and free-stream temperatures so that the temperature profile is either entirely subcritical (liquidlike), supercritical (gaslike), or transcritical (across the Widom line). The free-stream Mach number is set to <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mn>10</mn><mrow><mo>−</mo><mn>3</mn></mrow></msup></math>. In the nontranscritical regimes, the resulting streamwise-independent streaks originate from the lift-up effect. Wall cooling enhances the energy amplification for both subcritical and supercritical regimes. When the temperature profile is increased beyond the Widom line, a strong suboptimal growth is observed over very short streamwise distances due to the Orr mechanism. Due to the additional presence of transcritical Mode II, the optimal energy growth at large distances is found to arise from an interplay between lift-up and Orr mechanism. As a result, optimal disturbances are streamwise-modulated streaks with strong thermal components and with a propagation angle inversely proportional to the local Reynolds number. The nonmodal growth is put in perspective with modal growth by means of an <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>N</mi></math>-factor comparison. In the nontranscritical regimes, modal stability dominates regardless of a wall-temperature variation. In contrast, in the transcritical regime, nonmodal <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>N</mi></math> factors are found to resemble the imposition of an adverse pressure gradient in the ideal-gas regime. When cooling beyond the Widom line, optimal growth is greatly enhanced, yet strong inviscid instability prevails. When heating beyond the Widom line, optimal growth could be sufficiently large to favor transition, particularly with a high free-stream turbulence level.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"31 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883701","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":"Localized jammed clusters persist in shear-thickening suspension subjected to swirling excitation","authors":"Li-Xin Shi (石理新), Song-Chuan Zhao (赵松川)","doi":"10.1103/physrevfluids.9.083301","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.083301","url":null,"abstract":"We investigate the dynamic evolution of heterogeneity in shear-thickening suspensions subjected to swirling excitation with a free surface. The uniform state of such a system may lose its stability when the oscillation frequency is above a threshold, and density waves spontaneously form [Shi <i>et al.</i>, <span>J. Fluid Mech.</span> <b>984</b>, A69 (2024)]. Here, we report a state where jammed clusters emerge in high-density regions of the density waves. The jammed cluster exhibits unique motion, creating downstream high-density regions distinct from the previously reported state of density waves. Additionally, theoretical calculations show that reducing suspension thickness lowers the frequency and global concentration <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi mathvariant=\"normal\">Φ</mi></math> threshold for the heterogeneity onset. Notably, the minimal <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi mathvariant=\"normal\">Φ</mi></math> for instability can be lower than the onset of discontinuous shear thickening transition. We also highlight the role of the free surface in cluster growth and persistence.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"80 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883700","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":"From mixing to displacement of miscible phases in porous media: The role of heterogeneity and inlet pressures","authors":"Yahel Eliyahu-Yakir, Ludmila Abezgauz, Yaniv Edery","doi":"10.1103/physrevfluids.9.084501","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.084501","url":null,"abstract":"Miscible multiphase flow in porous media is a key phenomenon in various industrial and natural processes, such as hydrogen storage and geological carbon sequestration. However, the parameters controlling the patterns of displacement and mixing in these flows are not completely resolved. This study delves into the effects of heterogeneity and inlet pressure on mixing and displacement patterns of low-viscosity miscible phase invasion into a high-viscosity resident phase, that is saturating a porous medium. The findings highlight the substantial influence of inlet pressures and heterogeneity levels in transitioning from uniform to fingering patterns at the pore scale. These phenomena are detectable at the Darcy scale, and their transition from a uniform front to finger formation is effectively marked through a modified Sherwood number. This modified Sherwood number links microscale patterns to physical properties such as velocity distribution, diffusion, and viscosity contrasts. Additionally, the study employs breakthrough curve (BTC) analysis to illustrate the role of higher heterogeneity and inlet pressure in broadening the fluid velocity distribution, leading to the fingering pattern. These research insights provide a nondimensional approach that scales the BTCs, and can serve future models of miscible phase flow in porous media, linking pore-scale dynamics with macroscale Darcy-scale observations.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"57 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141887219","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}