Pub Date : 2024-09-03DOI: 10.1103/physrevfluids.9.094801
Jiyang Li, Zeng Liu, Alistair G. L. Borthwick, Jie Cui, Shijun Liao
Steady-state interfacial waves exhibiting class-III triad resonance are investigated in a two-layer liquid with a free surface. Two independent linear dispersion relationships related to surface and internal modes exist in the idealized model. One-dimensional class-III triad resonance requires the presence of two short surface wave modes and one long internal wave mode in a copropagating wave system. Convergent series solutions are achieved by the homotopy analysis method (HAM) for steady-state interfacial wave groups involving resonant triads and quartets. Unlike conventional progressive interfacial waves that have small surface amplitude and large interface amplitude, the free surface wave height is far larger than that of the internal interface waves because the resonance interactions comprise multiple surface wave modes and a single internal wave mode. As the upper layer thickness increases, energy from the interface is transported to the free surface, and energy in the whole wave system shifts from shorter to longer resonant triads and quartets. Our results indicate that steady-state interfacial waves with class-III exact and near-resonance interactions among surface and internal wave modes could occur in cases representative of the real ocean.
研究了具有自由表面的双层液体中表现出第三类三元共振的稳态界面波。在理想化模型中，存在两个与表面和内部模式相关的独立线性弥散关系。一维 III 级三元共振要求在共传播波系统中存在两个短表面波模式和一个长内波模式。对于涉及共振三元组和四元组的稳态界面波群，通过同调分析方法（HAM）获得了收敛序列解。与表面振幅小、界面振幅大的传统渐进界面波不同，自由表面波高度远大于内部界面波高度，因为共振相互作用包括多个表面波模式和一个内部波模式。随着上层厚度的增加，界面的能量被传输到自由表面，整个波系的能量从较短的共振三元组和四元组转移到较长的共振四元组。我们的研究结果表明，在具有代表性的真实海洋中，可能会出现具有第三类精确共振以及表面波和内波模式之间近共振相互作用的稳态界面波。
{"title":"Steady-state interfacial gravity waves with one-dimensional class-III triad resonance","authors":"Jiyang Li, Zeng Liu, Alistair G. L. Borthwick, Jie Cui, Shijun Liao","doi":"10.1103/physrevfluids.9.094801","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.094801","url":null,"abstract":"Steady-state interfacial waves exhibiting class-III triad resonance are investigated in a two-layer liquid with a free surface. Two independent linear dispersion relationships related to surface and internal modes exist in the idealized model. One-dimensional class-III triad resonance requires the presence of two short surface wave modes and one long internal wave mode in a copropagating wave system. Convergent series solutions are achieved by the homotopy analysis method (HAM) for steady-state interfacial wave groups involving resonant triads and quartets. Unlike conventional progressive interfacial waves that have small surface amplitude and large interface amplitude, the free surface wave height is far larger than that of the internal interface waves because the resonance interactions comprise multiple surface wave modes and a single internal wave mode. As the upper layer thickness increases, energy from the interface is transported to the free surface, and energy in the whole wave system shifts from shorter to longer resonant triads and quartets. Our results indicate that steady-state interfacial waves with class-III exact and near-resonance interactions among surface and internal wave modes could occur in cases representative of the real ocean.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"406 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210842","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}
Pub Date : 2024-09-03DOI: 10.1103/physrevfluids.9.093601
Yao-Jun Li, Yi-Zhou Liu, Yi-Bo Wang, Min Chen
In this paper, we experimentally investigate the rebound dynamics of droplets on dry ice surfaces, unveiling the mechanism behind the inverse Leidenfrost phenomenon. We demonstrated that the underlying mechanism driving the inverse Leidenfrost phenomenon is the lift force from the air film generated by the sublimation of dry ice. The air film prevents droplet condensation, facilitating the droplet rebound. However, the presence of film significantly depends on impact conditions. During the early spreading stage, bubbles nucleate at the contact line due to the sublimation, then the bubbles grow and gradually form an air film. We showed that the droplet rebound occurs only when the air film fully forms before the maximum spreading stage. Otherwise, the contact line is frozen, ultimately preventing rebound. We propose a theoretical expression of critical air film thickness that determines whether the droplet rebounds. Based on the expression, we ultimately established a theoretical criterion for droplet rebound via thermodynamic and fluid dynamics principles. To validate our developed theoretical criterion, we further investigated the inverse Leidenfrost phenomenon for different fluids, Weber numbers, and different temperatures of droplets. The results demonstrate a high consistency between the predicted results of our theoretical criterion and experimental results.
{"title":"Rebound dynamics of inverse Leidenfrost droplets on dry ice surfaces","authors":"Yao-Jun Li, Yi-Zhou Liu, Yi-Bo Wang, Min Chen","doi":"10.1103/physrevfluids.9.093601","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.093601","url":null,"abstract":"In this paper, we experimentally investigate the rebound dynamics of droplets on dry ice surfaces, unveiling the mechanism behind the inverse Leidenfrost phenomenon. We demonstrated that the underlying mechanism driving the inverse Leidenfrost phenomenon is the lift force from the air film generated by the sublimation of dry ice. The air film prevents droplet condensation, facilitating the droplet rebound. However, the presence of film significantly depends on impact conditions. During the early spreading stage, bubbles nucleate at the contact line due to the sublimation, then the bubbles grow and gradually form an air film. We showed that the droplet rebound occurs only when the air film fully forms before the maximum spreading stage. Otherwise, the contact line is frozen, ultimately preventing rebound. We propose a theoretical expression of critical air film thickness that determines whether the droplet rebounds. Based on the expression, we ultimately established a theoretical criterion for droplet rebound via thermodynamic and fluid dynamics principles. To validate our developed theoretical criterion, we further investigated the inverse Leidenfrost phenomenon for different fluids, Weber numbers, and different temperatures of droplets. The results demonstrate a high consistency between the predicted results of our theoretical criterion and experimental results.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"7 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210846","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}
Pub Date : 2024-09-03DOI: 10.1103/physrevfluids.9.094602
X. X. Li, R. F. Hu, L. Fang
Townsend's attached-eddy model (AEM) is one of the most widely used models in explaining and predicting the logarithmic region of wall turbulence. Townsend pioneered the postulate that wall-attached eddies exhibit self-similar velocity distributions. This premise has led to the derivation of velocity variance scalings in the logarithmic region. In particular, the attached eddies have been extracted at moderate scales and have been illustrated to contain the most kinetic energies in the logarithmic region. In the present contribution, we derive analytically the scalings of the moments of velocity gradients of attached eddies by using the AEM. The direct numerical simulation data with the moderate-scale extraction of attached eddies show good agreement with the derived scalings. Moreover, the contributions of different-scale structures to the moments of velocity gradients are compared, showing that the wall scalings of all-scale velocity gradients are interestingly half of moderate-scale attached eddies. This also indicates the non-negligible influence of the small-scale eddies on the velocity gradients in the logarithmic region. In addition, there are departures in the moments of velocity Hessian, inspiring future improvement in the extraction method of attached eddies.
{"title":"Scaling laws of velocity gradient moments of attached eddies","authors":"X. X. Li, R. F. Hu, L. Fang","doi":"10.1103/physrevfluids.9.094602","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.094602","url":null,"abstract":"Townsend's attached-eddy model (AEM) is one of the most widely used models in explaining and predicting the logarithmic region of wall turbulence. Townsend pioneered the postulate that wall-attached eddies exhibit self-similar velocity distributions. This premise has led to the derivation of velocity variance scalings in the logarithmic region. In particular, the attached eddies have been extracted at moderate scales and have been illustrated to contain the most kinetic energies in the logarithmic region. In the present contribution, we derive analytically the scalings of the moments of velocity gradients of attached eddies by using the AEM. The direct numerical simulation data with the moderate-scale extraction of attached eddies show good agreement with the derived scalings. Moreover, the contributions of different-scale structures to the moments of velocity gradients are compared, showing that the wall scalings of all-scale velocity gradients are interestingly half of moderate-scale attached eddies. This also indicates the non-negligible influence of the small-scale eddies on the velocity gradients in the logarithmic region. In addition, there are departures in the moments of velocity Hessian, inspiring future improvement in the extraction method of attached eddies.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"64 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210850","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}
Pub Date : 2024-09-03DOI: 10.1103/physrevfluids.9.094101
Ruben Lier
Odd viscosity is a transport coefficient that can occur when fluids experience breaking of parity and time-reversal symmetry. Previous knowledge indicates that cylinders in incompressible odd viscous fluids, under no-slip boundary conditions, do not exhibit lift force, a phenomenon that poses challenges for the experimental detection of odd viscosity. This study investigates the impact of slip in Stokes flow, employing the odd generalization of the Lorentz reciprocal theorem. Our findings reveal that, at linear order in slip length, lift does not manifest. Subsequently, we explore the scenario involving a thin sheet with momentum decay as well as that of a finite system size, demonstrating that for Stokes flow lift does occur for the second-order slip length contribution. We address cylinder flow beyond the Stokes approximation by solving the Oseen equation to obtain a fluid profile that shows an interplay between odd viscosity and inertia, and acquire an explicit expression for Oseen lift at leading order in slip length.
{"title":"Slip-induced odd viscous flow past a cylinder","authors":"Ruben Lier","doi":"10.1103/physrevfluids.9.094101","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.094101","url":null,"abstract":"Odd viscosity is a transport coefficient that can occur when fluids experience breaking of parity and time-reversal symmetry. Previous knowledge indicates that cylinders in incompressible odd viscous fluids, under no-slip boundary conditions, do not exhibit lift force, a phenomenon that poses challenges for the experimental detection of odd viscosity. This study investigates the impact of slip in Stokes flow, employing the odd generalization of the Lorentz reciprocal theorem. Our findings reveal that, at linear order in slip length, lift does not manifest. Subsequently, we explore the scenario involving a thin sheet with momentum decay as well as that of a finite system size, demonstrating that for Stokes flow lift does occur for the second-order slip length contribution. We address cylinder flow beyond the Stokes approximation by solving the Oseen equation to obtain a fluid profile that shows an interplay between odd viscosity and inertia, and acquire an explicit expression for Oseen lift at leading order in slip length.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"16 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210840","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}
Pub Date : 2024-09-03DOI: 10.1103/physrevfluids.9.094601
V. J. Valadão, T. Ceccotti, G. Boffetta, S. Musacchio
We study the temporal fluctuations of the flux of surface potential energy in surface quasi-geostrophic (SQG) turbulence. By means of high-resolution, direct numerical simulations of the SQG model in the regime of forced and dissipated cascade of temperature variance, we show that the instantaneous imbalance in the energy budget originates a subleading correction to the spectrum of the turbulent cascade. Using a multiple-scale approach combined with a dimensional closure we derive a theoretical prediction for the power-law behavior of the corrections, which holds for a class of turbulent transport equations known as turbulence. Further, we apply a method to disentangle the equilibrium and nonequilibrium contribution in the instantaneous spectra, which can be generalized to other turbulent systems.
{"title":"Nonequilibrium fluctuations of the direct cascade in surface quasi-geostrophic turbulence","authors":"V. J. Valadão, T. Ceccotti, G. Boffetta, S. Musacchio","doi":"10.1103/physrevfluids.9.094601","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.094601","url":null,"abstract":"We study the temporal fluctuations of the flux of surface potential energy in surface quasi-geostrophic (SQG) turbulence. By means of high-resolution, direct numerical simulations of the SQG model in the regime of forced and dissipated cascade of temperature variance, we show that the instantaneous imbalance in the energy budget originates a subleading correction to the spectrum of the turbulent cascade. Using a multiple-scale approach combined with a dimensional closure we derive a theoretical prediction for the power-law behavior of the corrections, which holds for a class of turbulent transport equations known as <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>α</mi></math> turbulence. Further, we apply a method to disentangle the equilibrium and nonequilibrium contribution in the instantaneous spectra, which can be generalized to other turbulent systems.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"80 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210847","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}
Pub Date : 2024-09-03DOI: 10.1103/physrevfluids.9.093301
A. Kordalis, Y. Dimakopoulos, J. Tsamopoulos
We consider the buoyancy-driven rise and interaction between two initially stationary and gravity-aligned bubbles of wide radii ratio and constant volume in an elasto-visco-plastic material, extending our previous work regarding bubbles of equal radii [Kordalis et al., Phys. Rev. Fluids8, 083301 (2023)]. Primarily we consider a 0.1% aqueous Carbopol solution and model its rheology with the Saramito-Herschel-Bulkley constitutive model. Initially, we investigate the dynamics for a specific initial separation distance in a wide range of bubble radii, and we determine the conditions leading to three distinct patterns: bubble approach, bubble separation, and establishment of a constant distance between them. Specifically, when the leading bubble (LB) is smaller than the trailing bubble (TB), the bubbles approach each other due to the smaller buoyancy of the leading bubble. Strong attraction also occurs when the ratio of buoyant over viscous force of both bubbles is considerable. On the other hand, when the size of the TB is such that this ratio is moderate or small, the pattern is dictated by the size of the LB: A significantly larger LB compared to the trailing one causes separation of the pair. On the contrary, an only slightly larger LB may result in the bubbles rising with the same terminal velocity establishing a constant distance between them, the magnitude of which is mainly determined by the elastic response of the surrounding medium. The coupling of a negative wake behind the LB with a slight modification of the stresses exerted at its rear pole generates this dynamic equilibrium. The same equilibrium may be achieved by other specific pairs of bubble sizes for different initial distances of the pair if a critical initial distance is exceeded. Below this critical value, the bubbles approach each other. Finally, we construct maps of the three patterns with trailing bubble radius versus bubble radii ratio for different initial separation distances and material properties.
{"title":"Hydrodynamic interaction between coaxially rising bubbles in elasto-visco-plastic materials: Bubbles with a wide range of relative sizes","authors":"A. Kordalis, Y. Dimakopoulos, J. Tsamopoulos","doi":"10.1103/physrevfluids.9.093301","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.093301","url":null,"abstract":"We consider the buoyancy-driven rise and interaction between two initially stationary and gravity-aligned bubbles of wide radii ratio and constant volume in an elasto-visco-plastic material, extending our previous work regarding bubbles of equal radii [Kordalis <i>et al.</i>, <span>Phys. Rev. Fluids</span> <b>8</b>, 083301 (2023)]. Primarily we consider a 0.1% aqueous Carbopol solution and model its rheology with the Saramito-Herschel-Bulkley constitutive model. Initially, we investigate the dynamics for a specific initial separation distance in a wide range of bubble radii, and we determine the conditions leading to three distinct patterns: bubble approach, bubble separation, and establishment of a constant distance between them. Specifically, when the leading bubble (LB) is smaller than the trailing bubble (TB), the bubbles approach each other due to the smaller buoyancy of the leading bubble. Strong attraction also occurs when the ratio of buoyant over viscous force of both bubbles is considerable. On the other hand, when the size of the TB is such that this ratio is moderate or small, the pattern is dictated by the size of the LB: A significantly larger LB compared to the trailing one causes separation of the pair. On the contrary, an only slightly larger LB may result in the bubbles rising with the same terminal velocity establishing a constant distance between them, the magnitude of which is mainly determined by the elastic response of the surrounding medium. The coupling of a negative wake behind the LB with a slight modification of the stresses exerted at its rear pole generates this dynamic equilibrium. The same equilibrium may be achieved by other specific pairs of bubble sizes for different initial distances of the pair if a critical initial distance is exceeded. Below this critical value, the bubbles approach each other. Finally, we construct maps of the three patterns with trailing bubble radius versus bubble radii ratio for different initial separation distances and material properties.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"90 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210843","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}
Pub Date : 2024-08-28DOI: 10.1103/physrevfluids.9.084006
Akhil Varma
It is known that, beyond a critical speed, the straight contact line of a partially -wetting liquid destabilizes into a corner. One of the earliest theoretical works exploring this phenomenon [Limat and Stone, Europhys. Lett.65, 365 (2004)] elicited a self-similar conical structure of the interface in the viscous regime. However, noting that inertia is not expected to be negligible at contact line speeds close to and beyond the critical value for many common liquids, we provide the leading-order inertial correction to their solution. In particular, we find the self-similar corrections to the interface shape as well as the flow field, and also determine their scaling with the capillary number. We find that inertia invariably modifies the interface into a cusplike shape with an increased film thickness. Furthermore, when incorporating contact line dynamics into the model, resulting in a narrowing of the corner as the contact line speed increases, we still observe an overall increase in the inertial contribution with speed despite the increased confinement.
众所周知，当速度超过临界值时，部分润湿液体的直线接触线会不稳定地变成拐角。探索这一现象的最早理论著作之一[Limat 和 Stone，Europhys. Lett. 65, 365 (2004)]提出了粘滞状态下界面的自相似锥形结构。然而，我们注意到，对于许多常见液体来说，在接触线速度接近或超过临界值时，惯性是不可忽略的。特别是，我们找到了界面形状和流场的自相似修正，并确定了它们与毛细管数的比例关系。我们发现，随着薄膜厚度的增加，惯性无一例外地将界面修正为尖顶状。此外，当将接触线动力学纳入模型时，随着接触线速度的增加，角会变窄，尽管封闭性增加，我们仍然观察到惯性贡献随速度的总体增加而增加。
{"title":"Weak-inertial effects on destabilized receding contact lines","authors":"Akhil Varma","doi":"10.1103/physrevfluids.9.084006","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.084006","url":null,"abstract":"It is known that, beyond a critical speed, the straight contact line of a partially -wetting liquid destabilizes into a corner. One of the earliest theoretical works exploring this phenomenon [Limat and Stone, <span>Europhys. Lett.</span> <b>65</b>, 365 (2004)] elicited a self-similar conical structure of the interface in the viscous regime. However, noting that inertia is not expected to be negligible at contact line speeds close to and beyond the critical value for many common liquids, we provide the leading-order inertial correction to their solution. In particular, we find the self-similar corrections to the interface shape as well as the flow field, and also determine their scaling with the capillary number. We find that inertia invariably modifies the interface into a cusplike shape with an increased film thickness. Furthermore, when incorporating contact line dynamics into the model, resulting in a narrowing of the corner as the contact line speed increases, we still observe an overall increase in the inertial contribution with speed despite the increased confinement.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"11 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210844","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}
Pub Date : 2024-08-28DOI: 10.1103/physrevfluids.9.083703
Yu Zhang, Kang Luo, Hongliang Yi, Anjun Liu, Jian Wu
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.
{"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}
Pub Date : 2024-08-28DOI: 10.1103/physrevfluids.9.083501
Rui Yang, Thijs van den Ham, Roberto Verzicco, Detlef Lohse, Sander G. Huisman
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 , 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 the flow is (partially) reversed. In general, the shape which melts the slowest is quite distinct from that of a disk.
我们报告了悬浮在淡水中并受自然对流影响的冰的融化动力学。通过直接数值模拟，我们研究了椭圆形物体在 2.32×104≤Ra≤7.61×108 条件下的熔化率，其中 Ra 是用冰与周围水的温差定义的瑞利数。我们发现，该系统在三个控制参数中表现出非单调行为。作为椭圆体长宽比的函数，熔化时间显示出明显的最小值，这与具有最小周长的圆盘不同。此外，随着 Ra 的增大，系统也呈现出非单调趋势，因为在 Ra 大和长宽比大的情况下，水流会分离，从而导致截然不同的动力学。最后，由于水的密度随温度的变化是非单调的，因此熔化率也非单调地取决于环境温度，因为在中间温度（4∘C - 7∘C）下，流动（部分）是反向的。一般来说，熔化速度最慢的形状与圆盘形状截然不同。
{"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}
Pub Date : 2024-08-27DOI: 10.1103/physrevfluids.9.083102
Nora Caroline Wild, Kartik V. Bulusu, Michael W. Plesniak
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 ” 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.
{"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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：