Physical Review Fluids最新文献

{"title":"Application of large eddy simulation models to electroconvection turbulence study with lattice Boltzmann method","authors":"Yu Zhang, Kang Luo, Hongliang Yi, Anjun Liu, Jian Wu","doi":"10.1103/physrevfluids.9.083703","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.083703","url":null,"abstract":"Electroconvection (EC) turbulence is an important branch of electrohydrodynamics (EHD). Because the turbulence model for EHD has not been well studied, in this work we apply the large eddy simulation (LES) to electrohydrodynamic turbulence based on the lattice Boltzmann method (LBM). The eddy-viscosity methods (the Smagorinsky and wall-adapting local eddy-viscosity models) are used to model the momentum equation, and the charge transport equation is modeled with the help of the turbulent Schmidt number. Three EC cases are chosen to test the reliability of the LBM-LES models, including two-dimensional (2D) EC turbulence in square and rectangular cells, and three-dimensional (3D) EC turbulence between two parallel plates. For 2D cases, the LES results are compared to the results of different numerical methods, including direct numerical simulation and LES. The long-time statistics of maximum velocity, charge current and its probability distribution, and flow evolution are used to validate the 2D EC turbulence. We also analyze the flow patterns and average characteristics for 3D cases. The LES results could capture the main flow features of EC turbulence for all cases, and demonstrate a good agreement when compared with references. The mentioned LBM-LES models have demonstrated reliability and high computational speed, making them suitable for further simulations of electrohydrodynamic turbulence.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"68 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210874","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":"Circular objects do not melt the slowest in water","authors":"Rui Yang, Thijs van den Ham, Roberto Verzicco, Detlef Lohse, Sander G. Huisman","doi":"10.1103/physrevfluids.9.083501","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.083501","url":null,"abstract":"We report on the melting dynamics of ice suspended in fresh water and subject to natural convective flows. Using direct numerical simulations we investigate the melt rate of ellipsoidal objects for <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>2.32</mn><mo>×</mo><msup><mn>10</mn><mn>4</mn></msup><mo>≤</mo><mtext>Ra</mtext><mo>≤</mo><mn>7.61</mn><mo>×</mo><msup><mn>10</mn><mn>8</mn></msup></mrow></math>, where Ra is the Rayleigh number defined with the temperature difference between the ice and the surrounding water. We reveal that the system exhibits nonmonotonic behavior in three control parameters. As a function of the aspect ratio of the ellipsoid, the melting time shows a distinct minimum that is different from a disk which has the minimum perimeter. Furthermore, also with Ra the system shows a nonmonotonic trend, since for large Ra and large aspect ratio the flow separates, leading to distinctly different dynamics. Lastly, since the density of water is nonmonotonic with temperature, the melt rate depends nonmonotonically also on the ambient temperature, as for intermediate temperatures <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mo>(</mo><mn>4</mn><msup><mspace width=\"0.16em\"></mspace><mo>∘</mo></msup><mi mathvariant=\"normal\">C</mi><mo> </mo><mo>–</mo><mo> </mo><mn>7</mn><msup><mspace width=\"0.16em\"></mspace><mo>∘</mo></msup><mi mathvariant=\"normal\">C</mi><mo>)</mo></mrow></math> the flow is (partially) reversed. In general, the shape which melts the slowest is quite distinct from that of a disk.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"177 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210848","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":"Vortex dynamics in healthy and pro-atherogenic carotid artery bifurcation models","authors":"Nora Caroline Wild, Kartik V. Bulusu, Michael W. Plesniak","doi":"10.1103/physrevfluids.9.083102","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.083102","url":null,"abstract":"Carotid artery atherosclerosis is a significant contributor to mortality in the United States. While it is recognized that low wall-shear stresses trigger plaque formation, there is a limited comprehension of the internal vortical structures that impact these stresses and how they differ between a healthy and a disease-prone, high-risk patient cohort. Our objective is to determine which driving factors, such as anatomical features (artery geometry) and mass-flow split, govern vortex behavior. Physiological pulsatile flow computational fluid dynamics simulations were performed on a “healthy” and a “disease-prone” carotid artery bifurcation model. Geometry and flow effects are investigated separately by simulating a third hybrid model having a healthy geometry with outlet boundary conditions imposing disease-prone flow conditions. This “unhealthy <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi mathvariant=\"normal\">Δ</mi><mi mathvariant=\"normal\">P</mi></mrow></math>” model recreated disease-prone mass-flow split and internal carotid artery sinus axial pressure gradient conditions in a healthy carotid artery bifurcation geometry. The results of our study revealed that the main vortex's time of formation is primarily dictated by carotid artery bifurcation geometry, whereas its lifespan is determined by the flow conditions. The main vortex's spatial expansion, as well as its circulation decay rate, are dictated by the geometry, not the flow conditions. We conclude that a high internal carotid artery mass flow rate and a higher favorable pressure gradient maximum magnitude occurring near peak systole are strong indicators of a high predisposition towards atherogenesis.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"4 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142227806","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":"Physics-informed machine-learning solution to log-layer mismatch in wall-modeled large-eddy simulation","authors":"Soju Maejima, Kazuki Tanino, Soshi Kawai","doi":"10.1103/physrevfluids.9.084609","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.084609","url":null,"abstract":"This study proposes a physics-informed machine learning to enable using the erroneous flow data at near-wall grid points as the input to the wall model in a wall-modeled large-eddy simulation (LES). The proposed neural network predicts the amount of numerical error in the near-wall grid-point data and inputs the physically correct flow variables into the wall model by correcting the near-wall error. The input and output features of the neural networks are selected based on the physical relations of the turbulent boundary layer for robustness against various Reynolds and Mach number conditions. The proposed neural networks allow the wall model to accurately predict the wall shear stress from the erroneous near-wall information and yields accurate predictions of the turbulence statistics. Additionally, the proposed physics-informed machine-learning approach reproduces the asymmetry in the probability density functions of the predicted wall shear stress observed in direct numerical simulations, while the conventional wall model with input away from the wall does not. The results suggest that using the near-wall information for wall modeling may increase the fidelity of the wall-modeled LES.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"17 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210849","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":"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":"Edge-wave phase shifts versus normal-mode phase tilts in an Eady problem with a sloping boundary","authors":"J. Mak, N. Harnik, E. Heifetz, G. Kumar, E. Q. Y. Ong","doi":"10.1103/physrevfluids.9.083905","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.083905","url":null,"abstract":"One mechanistic interpretation of baroclinic instability is that of mutual constructive interference of Rossby edge waves. The suppression of baroclinic instability over slopes has been widely established, where previous research argues that a sloping boundary modifies the properties of these Rossby edge waves, but does not provide a mechanistic explanation for the suppression that is valid over all parameter space. In the context of an Eady problem modified by the presence of a sloping boundary, we provide a mechanistic rationalization for baroclinic instability in the presence of slopes that is valid over all parameter space, via an equivalent formulation explicitly in terms of Rossby edge waves. We also highlight the differences between edge-wave phase shifts and normal-mode phase tilts, showing that the edge-wave phase shifts should be the ones that are mechanistically relevant, and normal-mode phase tilt is a potentially misleading quantity to use. Further, we present evidence that the edge-wave phase shifts but not normal-mode phase tilts are well correlated with geometric quantities diagnosed from an analysis framework based on eddy variance ellipses. The result is noteworthy in that the geometric framework makes no explicit reference to the edge-wave structures in its construction, and the correlation suggests the geometric framework can be used in problems where edge-wave structures are not so well defined or readily available. Some implications for parametrization of baroclinic instability and relevant eddy-mean feedbacks are discussed. For completeness, we also provide an explicit demonstration that the linear instability problem of the present modified Eady problem is parity-time symmetric, and speculate about some suggestive links between parity-time symmetry, shear instability, and the edge-wave interaction mechanism.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"68 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210845","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":"Viscous influences on impulsively generated focused jets","authors":"Xianggang Cheng, Xiao-Peng Chen, Hang Ding, Chun-Yu Zhang, Haibao Hu, Laibing Jia","doi":"10.1103/physrevfluids.9.l082001","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.l082001","url":null,"abstract":"Impulsively generated focused jets play a significant role in various applications, including inkjet printing, needle-free drug delivery, and microfluidic devices. As the demand for generating jets and droplets from medium to highly viscous liquids increases, understanding the role of viscosity in jetting dynamics becomes crucial. While previous studies have examined the viscous effects on walls, the impact on free surfaces has not been thoroughly understood. This study aims to bridge this gap by integrating experiments with numerical simulations to investigate the viscous effects on focused jet formation. We demonstrate that mass and momentum transfer along the tangential direction of the free surface contribute to focused jet formation, and viscosity plays a key role in this transfer process. The viscosity-induced diffusion of the shear flow and vorticity near the free surface reduces the jet speed. Based on experimental observations and simulation results, we propose an equation to predict the viscous jet velocity. These findings offer new perspectives on viscous interface dynamics in advanced manufacturing and biomedical applications.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"45 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210876","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}