Physical Review Fluids最新文献

{"title":"Cascades of turbulent kinetic energy and multicomponent scalars in a momentum-scalar coupling turbulence driven by multiple mechanisms under homogeneous and isotropic hypotheses","authors":"Wei Zhao","doi":"10.1103/physrevfluids.9.084610","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.084610","url":null,"abstract":"Momentum-scalar coupling turbulence, a phenomenon observed in both natural and engineering contexts, involves the intricate interaction between multicomponent scalars and multiscale forces (i.e., multiple coupling mechanisms), resulting in a wide array of manifestations. Despite its importance, limited research has been conducted to comprehend the influence of these multicomponent and multiple coupling mechanisms on turbulence cascades. Hence, this study aims to provide a preliminary and theoretical exploration into how these multiple coupling mechanisms govern the cascades of turbulent kinetic energy and multicomponent scalars. To simplify the mathematical analysis, homogeneous and isotropic hypotheses of flow field have been applied. The key findings of this study can be summarized as follows. The first is validation of quad-cascade processes. The second is an examination of various cases involving single scalar components but multiple coupling mechanisms. Of particular interest is the coexistence of buoyancy-driven turbulence and electrokinetic turbulence, which introduces a new variable flux (VF) subrange resulting from their nonlinear interaction. Another extension considers an exponential modulation function, equivalent to the coexistence of multiple coupling mechanisms acting on a single scalar. The study identifies two new VF subranges. Third, binary scalar components and coupling mechanisms are investigated, indicating coupling mechanisms with significantly different strengths that can also induce complex interactions and new VF subranges. Fourth is the complexity when three or more different scalar components and coupling mechanisms coexist simultaneously: with the exception of certain special cases, closure of the problem becomes unattainable. This highlights the challenges inherent in addressing the simultaneous presence of multiple scalar components and coupling mechanisms. This research endeavor illuminates the theoretical understanding of the diverse scaling properties observed in momentum-scalar coupling turbulence across different scenarios.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"10 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142227807","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":"Surfactant-laden bubble bursting: Dynamics of capillary waves and Worthington jet at large Bond number","authors":"P. Pico, L. Kahouadji, S. Shin, J. Chergui, D. Juric, O. K. Matar","doi":"10.1103/physrevfluids.9.083606","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.083606","url":null,"abstract":"We present a numerical study of the main substages preceding aerosol formation via bursting bubbles: capillary wave propagation along the bubble, convergence at the bubble's apex, and the ascent of a Worthington jet and its breakup to release liquid drops. We focus on two crucial yet overlooked aspects of the system: the presence of surface-active agents and dynamics driven by non-negligible gravitational effects, quantified by the Bond number. Our results propose a mechanism explaining capillary wave retardation in the presence of surfactants, involving the transition from bi- to unidirectional Marangoni stresses, which pull the interface upwards, countering the motion of the waves. We also quantitatively elucidate the variable nature of the waves' velocity with various surfactant parameters, including surfactant solubility and elasticity, a departure from the constant behavior well documented in clean interfaces.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"177 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210862","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":"Robust experimental data assimilation for the Spalart-Allmaras turbulence model","authors":"Deepinder Jot Singh Aulakh, Xiang Yang, Romit Maulik","doi":"10.1103/physrevfluids.9.084608","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.084608","url":null,"abstract":"This study presents a methodology focusing on the use of computational model and experimental data fusion to improve the Spalart-Allmaras (SA) closure model for Reynolds-averaged Navier-Stokes solutions. In particular, our goal is to develop a technique that not only assimilates sparse experimental data to improve turbulence model performance, but also preserves generalization for unseen cases by recovering classical SA behavior. We achieve our goals using data assimilation, namely the ensemble Kalman filtering approach, to calibrate the coefficients of the SA model for separated flows. A holistic calibration strategy is implemented via the parametrization of the production, diffusion, and destruction terms. This calibration relies on the assimilation of experimental data collected in the form of velocity profiles, skin friction, and pressure coefficients. Despite using observational data from a single flow condition around a backward-facing step (BFS), the recalibrated SA model demonstrates generalization to other separated flows, including cases such as the two-dimensional (2D) NASA wall mounted hump and the modified BFS. Significant improvement is observed in the quantities of interest, i.e., the skin friction coefficient <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mo>(</mo><msub><mi>C</mi><mi>f</mi></msub><mo>)</mo></math> and the pressure coefficient <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mo>(</mo><msub><mi>C</mi><mi>p</mi></msub><mo>)</mo></math>, for each flow tested. Finally, it is also demonstrated that the newly proposed model recovers SA proficiency for flows, such as a NACA-0012 airfoil and axisymmetric jet, and that the individually calibrated terms in the SA model target specific flow-physics wherein the calibrated production term improves the recirculation zone while destruction improves the recovery zone.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"17 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210852","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":"Self-scaling generalized Townsend-Perry constants for high-order moments in turbulent boundary layers","authors":"Xibo He, Hongyou Liu, Xiaojing Zheng","doi":"10.1103/physrevfluids.9.l082602","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.l082602","url":null,"abstract":"Inspired by the thought-provoking paper of Meneveau and Marusic [<span>J. Fluid Mech.</span> <b>719</b>, R1 (2013)], the universal expression of the self-scaling generalized Townsend-Perry constants for the high-order statistical moments is investigated. The measured results deviate from the previous attached-eddy-model–based Gaussian prediction because the wall-non-attached eddies with sub-Gaussian statistics mask the Gaussian behavior of the wall-attached eddies. Leveraging the generalized Gaussian distribution function and the logarithmic law for turbulence intensity, the universal expression of the self-scaling generalized Townsend-Perry constants, regardless of the eddy type, is derived. Moreover, asymptotic expression of the shape parameter in self-scaling generalized Townsend-Perry constants with Reynolds number is further characterized by data in boundary layers and atmospheric surface layers with Reynolds number <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>R</mi><msub><mi>e</mi><mi>τ</mi></msub></mrow></math> spanning over <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>O</mi><mo>(</mo><msup><mn>10</mn><mn>3</mn></msup><mo>)</mo></mrow></math> to <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>O</mi><mo>(</mo><msup><mn>10</mn><mn>6</mn></msup><mo>)</mo></mrow></math>.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"1 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210856","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":"Translation of a sphere towards a rigid plane in an Oldroyd-B fluid","authors":"Tachin Ruangkriengsin, Rodolfo Brandão, Bimalendu Mahapatra, Evgeniy Boyko, Howard A. Stone","doi":"10.1103/physrevfluids.9.083303","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.083303","url":null,"abstract":"We analyze the low-Reynolds-number translation of a sphere towards or away from a rigid plane in an Oldroyd-B fluid under two scenarios: prescribing the sphere's translational velocity, and prescribing the force on the sphere. Leveraging the lubrication approximation and a perturbation expansion in powers of the Deborah number, we develop a comprehensive theoretical analysis that yields analytical approximations for velocity fields, pressures, and forces acting on the sphere. Our framework aids in understanding temporal microstructural changes as the particle-wall gap evolves over time. In particular, we show that alterations in the polymer conformation tensor in response to geometric changes induce additional forces on the sphere. For cases with prescribed velocity, we present a theoretical approach for calculating resistive forces at any order in the Deborah number and utilize a reciprocal theorem to obtain higher-order corrections based on velocity fields in the previous orders. When the sphere translates with a constant velocity, the fluid viscoelasticity decreases the resistive force at the first order. However, at the second-order correction, the direction of the sphere's movement determines whether viscoelasticity increases or decreases the resistive force. For cases with prescribed force, we show that understanding the influence of viscoelasticity on the sphere's translational velocity necessitates a more intricate analysis even at low Deborah numbers. Specifically, we introduce an ansatz for constant force scenarios, and we derive solution forms for general prescribed forces using the method of multiple scales. We find that when a sphere undergoes sedimentation due to its own weight, the fluid viscoelasticity results in a slower settling process, reducing the leading-order sedimentation rate.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"33 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210851","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":"Tones and upstream-traveling waves in ideally expanded round impinging jets","authors":"Igor A. Maia, Maxime Fiore, Romain Gojon","doi":"10.1103/physrevfluids.9.083904","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.083904","url":null,"abstract":"We study the generation of tones by ideally expanded round jets impinging on a flat plate. Data from large-eddy simulations performed for different nozzle-to-plate distances are explored, and we consider closure of the aeroacoustic feedback loop responsible for the tones by guided jet modes. Allowable frequency ranges for resonance, underpinned by the existence of modes with upstream-directed group velocities, are computed using two different models: a cylindrical vortex-sheet model, and a locally parallel stability model which considers a finite-thickness velocity profile. It is shown that inclusion of a finite-thickness velocity profile consistent with the mean flow in the vicinity of the plate improves the agreement between observed tones and model predictions. The frequencies of the largest tones found in the data are found to fall within, or very close to, the frequency limits of the finite-thickness model, correcting discrepancies observed with the vortex-sheet model. The same trend is observed in comparisons with experimental and numerical data gathered from the literature. Pressure eigenfunctions of the stability model are in good agreement with upstream-traveling disturbances educed from the data at the tone frequencies. This provides further evidence for the involvement of guided jet modes in the resonance mechanism.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"12 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142227809","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":"Single theoretical model for breakup of viscous thread with and without a fiber","authors":"Hyejoon Jun, Hyoungsoo Kim","doi":"10.1103/physrevfluids.9.084005","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.084005","url":null,"abstract":"In this study, we introduce a comprehensive theoretical model for viscous liquid systems exhibiting Rayleigh-Plateau instability, accommodating cases both with and without a solid fiber. Employing the lubrication approach and implementing the hydrodynamic interaction at the solid-liquid interface, we formulate one-dimensional evolution equations for the breakup of viscous liquid threads and films on a fiber. Through several validations, we showed that our model exhibits a good agreement with experimental results in comparison to numerical simulations. Finally, our model, which incorporates the flow effect from the inner boundary condition by reconsidering the ansatz of a conventional long-wave approximation, provides a necessary condition for satellite droplet formation and determines the most unstable mode proportional to <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mrow><msup><mi>k</mi><mo>*</mo></msup></mrow><mn>2</mn></msup></math>, where <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mi>k</mi><mo>*</mo></msup></math> is the most unstable wavenumber. In addition, we observed that the volume of the satellite droplets exponentially decays depending on the wavenumber. Moreover, our single model integrates the findings of Goren's liquid film on a fiber and Rayleigh's viscous liquid thread, demonstrating its versatility and relevance to a wide range of systems.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"49 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210866","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":"Convection in the active layer speeds up permafrost thaw in coarse-grained soils","authors":"M. Magnani, S. Musacchio, A. Provenzale, G. Boffetta","doi":"10.1103/physrevfluids.9.l081501","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.l081501","url":null,"abstract":"Permafrost thaw is a major concern raised by the ongoing climate change. An understudied phenomenon possibly affecting the pace of permafrost thaw is the onset of convective motions within the active layer caused by the density anomaly of water. Here we explore the effects of groundwater convection on permafrost thawing using a model that accounts for ice-water phase transitions, coupled with the dynamics of the temperature field transported by the Darcy's flow across a porous matrix. Numerical simulations of this model show that ice thawing in the presence of convection is much faster than in the diffusive case and deepens at a constant velocity proportional to the soil permeability. A scaling argument is able to predict correctly the asymptotic velocity. Since in the convective regime the heat transport is mediated by the coherent motion of thermal plumes across the thawed layer, we find that the depth of the thawing interface becomes highly heterogeneous.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"62 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210858","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":"Data-driven low-dimensional model of a sedimenting flexible fiber","authors":"Andrew J. Fox, Michael D. Graham","doi":"10.1103/physrevfluids.9.084101","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.084101","url":null,"abstract":"The dynamics of flexible filaments entrained in flow, important for understanding many biological and industrial processes, are computationally expensive to model with full physics simulations. In this paper, we describe a data-driven technique to create high-fidelity low-dimensional models of flexible fiber dynamics using machine learning; the technique is applied to sedimentation in a quiescent, viscous Newtonian fluid, using results from detailed simulations as the dataset. The approach combines an autoencoder neural network architecture to learn a low-dimensional latent representation of the filament shape, with a neural ordinary differential equation that learns the evolution of the particle in the latent state. The model was designed to model filaments of varying flexibility, characterized by an elastogravitational number <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi mathvariant=\"script\">B</mi></math>, and was trained on a dataset containing the evolution of fibers beginning at set angles of inclination. For the range of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi mathvariant=\"script\">B</mi></math> considered here (100–10 000), the filament shape dynamics can be represented with high accuracy with only four degrees of freedom, in contrast with the 93 present in the original bead-spring model used to generate the dynamic trajectories. We predict the evolution of fibers set at arbitrary angles and demonstrate that our data-driven model can accurately forecast the evolution of a fiber at both trained and untrained elastogravitational numbers.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"30 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210873","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":"Flooding as a sub-critical instability in open channels","authors":"Serge Mora, Martine Le Berre, Yves Pomeau","doi":"10.1103/physrevfluids.9.084607","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.084607","url":null,"abstract":"In flood events caused by a gradual increase in the flow rate of a watercourse, the rise in water level is often abrupt, while the fall in level is delayed. We show that such behavior can be demonstrated by considering stationary flows at a high Reynolds number in a prismatic open channel: Several geometries of the channel cross section lead to a subcritical instability that results in a discontinuous rise in the level when the flow rate exceeds a critical value <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>F</mi><mi>i</mi></msub></math>, and in a fall, also discontinuous, when the flow rate returns below a value <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>F</mi><mi mathvariant=\"script\">o</mi></msub></math> lower than <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>F</mi><mi>i</mi></msub></math>. This hysteretic behavior originates from the interplay between gravity, which drives the flow downstream, and turbulent friction with the channel wall. The potential existence of several solutions arising from this bifurcation requires careful consideration in flood simulations.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"100 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210863","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}