Physical Review Fluids最新文献

{"title":"Evidence of a finite-time pointlike singularity solution for the Euler equations for perfect fluids","authors":"Diego Martínez-Argüello, Sergio Rica","doi":"10.1103/physrevfluids.9.094401","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.094401","url":null,"abstract":"This paper investigates the evolution of the Euler equations near a potential blow-up solution. We employ an approach where this solution exhibits second-type self-similarity, characterized by an undetermined exponent <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>ν</mi></math>. This exponent can be seen as a nonlinear eigenvalue, determined by the solution of a self-similar partial differential equation with appropriate boundary conditions. Specifically, we demonstrate the existence of an axisymmetric solution of the Euler equations by expanding the axial vorticity using associated Legendre polynomials as a basis. This expansion results in an infinite hierarchy of ordinary differential equations, which, when truncated up to a certain order <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mi>N</mi><mo>*</mo></msup></math>, allows for the numerical resolution of a finite set of ordinary differential equations. Through this numerical analysis, we obtain a solution that satisfies the appropriate boundary conditions for a specific value of the exponent <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>ν</mi></math>. By exploring various truncations, we establish a sequence in <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msup><mi>N</mi><mo>*</mo></msup></math> for the parameter <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>ν</mi><msup><mi>N</mi><mo>*</mo></msup></msub></math>, providing evidence of the convergence of the exponent <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>ν</mi></math>. Our findings suggest a self-similar exponent <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>ν</mi><mo>≈</mo><mn>2</mn></mrow></math>, presenting a promising path for a numerical or analytical approach indicating that <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>ν</mi></math> may indeed be exactly 2.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"12 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142210966","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":"Helicity transfer in compressible turbulent flows","authors":"Zheng Yan, Junfeng Wu, Zhu Lei, Jianchun Wang, Lifeng Wang, Xinliang Li, Changping Yu","doi":"10.1103/physrevfluids.9.094603","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.094603","url":null,"abstract":"The dual-channel characteristics of large-scale helicity transfer in compressible turbulent flows, including subgrid-scale (SGS) and viscosity terms, are investigated. After selecting a suitable definition for large-scale helicity, we confirm the existence of the dual channel of SGS and viscosity terms of large-scale helicity governing equations and theoretically prove that no dual pressure term channel exists. The second channel of the SGS and viscosity terms also consists of two terms, which originate from the rotation of the SGS stress and the baroclinic of the velocity and density gradients, respectively. The identical relationship of the ensemble averages of the dual channel of SGS and viscosity terms can be theoretically and numerically confirmed, whereas their second channel which is associated with shocklets is more intermittent. For the SGS term, the compression regions are dominant in contrast to the expansion regions, and the strain regions are dominant in contrast to the rotation regions in the inertial scale range. The viscous dissipation mechanism of large-scale helicity differs from that of large-scale kinetic energy. It is dominated by the first channel on the inside of the vortex structure and by the second channel on the outside. The further decompositions of the second channel of the SGS and viscosity terms provide a possible mechanism for the inverse helicity transfer. This means that expansion motions promote inverse helicity transfer through the second terms of their second channels.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"1 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142227910","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":"Efficient dynamic mixed subgrid-scale model","authors":"Prahladh S. Iyer, Mujeeb R. Malik","doi":"10.1103/physrevfluids.9.l092601","DOIUrl":"https://doi.org/10.1103/physrevfluids.9.l092601","url":null,"abstract":"It is well known that the scale-similarity class of subgrid models have a high correlation with the actual subgrid stresses in <i>a priori</i> tests. However, these models are typically underdissipative and not robust enough to be practically useful for large-eddy simulation. On the other hand, the dynamic Smagorinsky model (DSM), which is a popular subgrid model, is sufficiently dissipative and robust, but has a lower correlation with actual subgrid stresses in <i>a priori</i> tests. There have been many successful attempts to combine the two models into a “mixed” subgrid model that have typically retained the favorable properties of both. However, most dynamic mixed models require two or more levels of test filtering beyond the (often implicit) grid filtered quantities that are solved, in contrast to a single test filtering operation for the dynamic Smagorinsky model. The additional cost involved in test filtering has likely hindered the widespread use of dynamic mixed models in production codes. We propose an efficient dynamic mixed model that is constrained to have the same subgrid dissipation as the DSM model, and only requires a single level of test filtering. Thus, the additional computational cost is negligible compared to the DSM model. <i>A posteriori</i> simulations of the turbulent channel flow reveal that the proposed mixed model is as robust as the DSM model, and more accurate on coarser grids. Notably, smooth-body turbulent separation is better captured by the new model when combined with a standard wall model.","PeriodicalId":20160,"journal":{"name":"Physical Review Fluids","volume":"6 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142227909","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":"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}

{"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}

{"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}

{"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}

{"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}

{"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}

{"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}