arXiv: Fluid Dynamics最新文献

Reproduction of vortex lattices in the simulations of rotating liquid helium-4 by numerically solving the two-fluid model using smoothed-particle hydrodynamics incorporating vortex dynamics 用含涡旋动力学的光滑粒子流体力学数值求解双流体模型模拟旋转液氦-4的涡旋晶格再现

arXiv: Fluid Dynamics Pub Date : 2021-05-07 DOI: 10.1063/5.0060605

Satori Tsuzuki

{"title":"Reproduction of vortex lattices in the simulations of rotating liquid\u0000 helium-4 by numerically solving the two-fluid model using smoothed-particle hydrodynamics\u0000 incorporating vortex dynamics","authors":"Satori Tsuzuki","doi":"10.1063/5.0060605","DOIUrl":"https://doi.org/10.1063/5.0060605","url":null,"abstract":"Our recent study has shown that the representative phenomena of liquid helium-4 rotating in a cylinder could be simulated by solving the two-fluid model using smoothed-particle hydrodynamics (SPH) after reformulating the viscosity to conserve the rotational angular momentum. Specifically, the emergence of multiple parallel vortices and their rigid-body rotations were observed in our previous SPH simulations. The reported scheme is based on a classical approximation that assumes the fluid forces of both components and their interactions, with the expectation of functioning as a coarse-grained model of existing approximations that couple a microscopic model and the Navier-Stokes equation. Based on previous studies, this paper proposes an improved SPH scheme that explicitly incorporates vortex dynamics into SPH to reproduce vortex lattices, which was not possible in previous studies. Consequently, our improved scheme was observed to reproduce vortex lattices by introducing the Magnus force and the interaction forces among vortices into the reformulated two-fluid model. The spinnings of the vortices and rigid-body rotations were also observed. The number of vortices showed a certain agreement with Feynman's rule after the model parameter was optimized. Notably, from a scientific point of view, such vortex lattices are reproduced by the classical-mechanical approximation. We hope that our model will help physicists studying low-temperature physics find a new way of approaching this bizarre phenomenon that has attracted attention for more than 80 years.","PeriodicalId":328276,"journal":{"name":"arXiv: Fluid Dynamics","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126187214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 8

Surface wave scattering by multiple flexible fishing cage system 多柔性网箱系统的表面波散射

arXiv: Fluid Dynamics Pub Date : 2020-12-17 DOI: 10.1063/5.0040662

S. A. Selvan, R.Gayathri, H. Behera, M. Meylan

{"title":"Surface wave scattering by multiple flexible fishing cage system","authors":"S. A. Selvan, R.Gayathri, H. Behera, M. Meylan","doi":"10.1063/5.0040662","DOIUrl":"https://doi.org/10.1063/5.0040662","url":null,"abstract":"A study of the wave dynamics around a multiple fishing cage system is carried out under the assumption of the linear water wave theory and small-amplitude wave response. The Fourier--Bessel series expansion of the velocity potential is derived for regions enclosed under the open-water and cage systems and in the immediate vicinity. Further, the scattering between the cages is accounted for by employing Graf's addition theorem. The porous flexible cage system is modelled using Darcy's law and the three-dimensional membrane equation. The edges of the cages are moored along its circumferences to balance its position in the deep sea. The unknown coefficients in the potentials are obtained by employing the matched eigenfunction method in conjunction with the least-squares approximation method. In addition, the far-field scattering coefficients for the entire system are obtained by expanding the Bessel and Hankel functions in the plane wave representation form. Numerical results such as the hydrodynamic forces, scattering coefficients, and power dissipation are investigated for various cage and wave parameters. The wave loading on the cage system can be significantly damped by the spatial arrangement, membrane tension, and porous-effect parameter. Moreover, the far-field results suggest that the cage system can also be used as a breakwater.","PeriodicalId":328276,"journal":{"name":"arXiv: Fluid Dynamics","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125570069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 23

Capillary fluctuations and energy dynamics for flow in porous media 多孔介质中流动的毛细波动和能量动力学

arXiv: Fluid Dynamics Pub Date : 2020-12-16 DOI: 10.1063/5.0057428

J. McClure, S. Berg, R. Armstrong

引用次数: 15

An implicit kinetic inviscid flux for predicting continuum flows in all speed regimes 用于预测所有速度范围内连续流的隐式动力学无粘通量

arXiv: Fluid Dynamics Pub Date : 2020-12-15 DOI: 10.1063/5.0044107

Jun Cao, Sha Liu, Chengwen Zhong, Congshan Zhuo

{"title":"An implicit kinetic inviscid flux for predicting continuum flows in all speed regimes","authors":"Jun Cao, Sha Liu, Chengwen Zhong, Congshan Zhuo","doi":"10.1063/5.0044107","DOIUrl":"https://doi.org/10.1063/5.0044107","url":null,"abstract":"In this study, the kinetic inviscid flux (KIF) is improved and an implicit strategy is coupled. The recently proposed KIF is a kind of inviscid flux, whose microscopic mechanism makes it good at solving shock waves, with advantages against the shock instability phenomenon. When developing the implicit KIF, a phenomenon is noticed that the kinetic flux vector splitting (KFVS) part in boundary layers not only reduces the accuracy, but seriously reduces the Courant-Friedrichs-Lewy (CFL) number as well. As a result, in this paper, a new weight is proposed about how to combine the KFVS method well with the totally thermalized transport (TTT) method. Besides admitting the using of larger CFL numbers, this new weight brings about more accurate numerical results like pressure, friction coefficient and heat flux when solving shock waves, boundary layers and complex supersonic/hypersonic flows. In order to examine the validity, accuracy and efficiency of the present method, six numerical test cases, covering the whole speed regime, are conducted, including the hypersonic viscous flow past a cylinder, the hypersonic double-cone flow, the hypersonic double-ellipsoid flow, the laminar shock boundary layer interaction, the supersonic flow around a ramp segment and the lid-driven cavity flow. The advantages of this scheme and corresponding mechanisms are to be discussed in detail.","PeriodicalId":328276,"journal":{"name":"arXiv: Fluid Dynamics","volume":"348 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130929988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Paths to caustic formation in turbulent aerosols 湍流气溶胶中腐蚀性形成的路径

arXiv: Fluid Dynamics Pub Date : 2020-12-15 DOI: 10.1103/PhysRevFluids.6.L062302

J. Meibohm, Vikas Pandey, Akshay Bhatnagar, K. Gustavsson, D. Mitra, P. Perlekar, B. Mehlig

引用次数: 6

Filtering, averaging, and scale dependency in homogeneous variable density turbulence 均匀变密度湍流中的滤波、平均和尺度依赖性

arXiv: Fluid Dynamics Pub Date : 2020-12-12 DOI: 10.1063/5.0040337

J. Saenz, D. Aslangil, D. Livescu

{"title":"Filtering, averaging, and scale dependency in homogeneous variable density turbulence","authors":"J. Saenz, D. Aslangil, D. Livescu","doi":"10.1063/5.0040337","DOIUrl":"https://doi.org/10.1063/5.0040337","url":null,"abstract":"We investigate relationships between statistics obtained from filtering and from ensemble or Reynolds-averaging turbulence flow fields as a function of length scale. Generalized central moments in the filtering approach are expressed as inner products of generalized fluctuating quantities, $q'(xi,x)=q(xi)-overline q(x)$, representing fluctuations of a field $q(xi)$, at any point $xi$, with respect to its filtered value at $x$. For positive-definite filter kernels, these expressions provide a scale-resolving framework, with statistics and realizability conditions at any length scale. In the small-scale limit, scale-resolving statistics become zero. In the large-scale limit, scale-resolving statistics and realizability conditions are the same as in the Reynolds-averaged description. Using direct numerical simulations (DNS) of homogeneous variable density turbulence, we diagnose Reynolds stresses, $mathcal{T}_{ij}$, resolved kinetic energy, $k_r$, turbulent mass-flux velocity, $a_i$, and density-specific volume covariance, $b$, defined in the scale-resolving framework. These variables, and terms in their governing equations, vary smoothly between zero and their Reynolds-averaged definitions at the small and large scale limits, respectively. At intermediate scales, the governing equations exhibit interactions between terms that are not active in the Reynolds-averaged limit. For example, in the Reynolds-averaged limit, $b$ follows a decaying process driven by a destruction term; at intermediate length scales it is a balance between production, redistribution, destruction, and transport, where $b$ grows as the density spectrum develops, and then decays when mixing becomes strong enough. This work supports the notion of a generalized, length-scale adaptive model that converges to DNS at high resolutions, and to Reynolds-averaged statistics at coarse resolutions.","PeriodicalId":328276,"journal":{"name":"arXiv: Fluid Dynamics","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129106077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 9

Two- and three-dimensional simulations of Rayleigh–Taylor instabilities using a coupled Cahn–Hilliard/Navier–Stokes model 利用耦合Cahn-Hilliard / Navier-Stokes模型对瑞利-泰勒不稳定性进行二维和三维模拟

arXiv: Fluid Dynamics Pub Date : 2020-12-11 DOI: 10.1063/5.0031179

R. Zanella, G. Tegze, R. Le Tellier, H. Henry

{"title":"Two- and three-dimensional simulations of Rayleigh–Taylor instabilities using a coupled Cahn–Hilliard/Navier–Stokes model","authors":"R. Zanella, G. Tegze, R. Le Tellier, H. Henry","doi":"10.1063/5.0031179","DOIUrl":"https://doi.org/10.1063/5.0031179","url":null,"abstract":"We report on two- and three-dimensional numerical simulations of Rayleigh-Taylor instabilities in immiscible fluids. A diffuse-interface model that combines the Cahn-Hilliard equation, governing the evolution of the volume fraction of one fluid, and the Navier-Stokes equations, governing the bulk velocity and pressure, is used. The study is limited to low Atwood numbers owing to the use of the Boussinesq approximation. The code is based on a pseudo-spectral method. A linear analysis is first performed in a two-dimensional case of Rayleigh-Taylor instability to confirm that the model very well captures this phenomenon in the case of inviscid or viscid fluids. One key aspect of this work is that the influence of the thermodynamic parameters related to the Cahn-Hilliard equation (interface thickness and mobility) is quantitively studied. Three-dimensional results of Rayleigh-Taylor instabilities in viscous fluids are then presented to show the possibilities of this modeling. We observe the effect of the viscosity and the wavelength of an initial single-mode perturbation on the mass transport during the nonlinear regime.","PeriodicalId":328276,"journal":{"name":"arXiv: Fluid Dynamics","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121779721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 22

Measurement of the deposit formation during pneumatic transport of polydisperse PMMA powder 聚甲基丙烯酸甲酯(PMMA)多分散粉体气力输送过程中沉积物形成的测量

arXiv: Fluid Dynamics Pub Date : 2020-12-09 DOI: 10.7795/810.20200724

Nuki Susanti, H. Grosshans

引用次数: 4

Stochastic mesoscale circulation dynamics in the thermal ocean 热海洋随机中尺度环流动力学

arXiv: Fluid Dynamics Pub Date : 2020-12-08 DOI: 10.1063/5.0040026

Darryl D. Holm, Erwin Luesink, Wei Pan

{"title":"Stochastic mesoscale circulation dynamics in the thermal ocean","authors":"Darryl D. Holm, Erwin Luesink, Wei Pan","doi":"10.1063/5.0040026","DOIUrl":"https://doi.org/10.1063/5.0040026","url":null,"abstract":"In analogy with similar effects in adiabatic compressible fluid dynamics, the effects of buoyancy gradients on incompressible stratified flows are said to be `thermal'. The thermal rotating shallow water (TRSW) model equations contain three small nondimensional parameters. These are the Rossby number, the Froude number and the buoyancy parameter. Asymptotic expansion of the TRSW model equations in these three small parameters leads to the deterministic thermal versions of the Salmon's L1 (TL1) model and the thermal quasi-geostrophic (TQG) model, upon expanding in the neighbourhood of thermal quasi-geostrophic balance among the flow velocity and the gradients of free surface elevation and buoyancy. The linear instability of TQG at high wave number tends to create circulation at small scales. Such a high wave number instability could be unresolvable in many computational simulations, but its presence at small scales may contribute significantly to fluid transport at resolvable scales. Sometimes such effects are modelled via `stochastic backscatter of kinetic energy'. Here we try another approach. Namely, we model `stochastic transport' in the hierarchy of models TRSW/TL1/TQG. The models are derived via the approach of stochastic advection by Lie transport (SALT) as obtained from a recently introduced stochastic version of the Euler--Poincar'e variational principle. We also indicate the potential next steps for applying these models in uncertainty quantification and data assimilation of the rapid, high wavenumber effects of buoyancy fronts at these three levels of description by using the data-driven stochastic parametrisation algorithms derived previously using the SALT approach.","PeriodicalId":328276,"journal":{"name":"arXiv: Fluid Dynamics","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115886752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 14

Ultrasonic oscillatory two-phase flow in microchannels 微通道超声振荡两相流

arXiv: Fluid Dynamics Pub Date : 2020-12-07 DOI: 10.1063/5.0039971

Zhaokuan Lu, Éric Dupuis, V. Patel, A. Momen, S. Shahab

{"title":"Ultrasonic oscillatory two-phase flow in microchannels","authors":"Zhaokuan Lu, Éric Dupuis, V. Patel, A. Momen, S. Shahab","doi":"10.1063/5.0039971","DOIUrl":"https://doi.org/10.1063/5.0039971","url":null,"abstract":"Experimental and numerical investigations are performed to provide an assessment of the transport behavior of an ultrasonic oscillatory two-phase flow in a microchannel. The work is inspired by the flow observed in an innovative ultrasonic fabric drying device using a piezoelectric bimorph transducer with microchannels, where a water-air two-phase flow is transported by harmonically oscillating microchannels. The flow exhibits highly unsteady behavior as the water and air interact with each other during the vibration cycles, making it significantly different from the well-studied steady flow in microchannels. The computational fluid dynamics (CFD) modeling is realized by combing the turbulence Reynolds-averaged Navier-Stokes (RANS) k-${omega}$ model with the phase-field method to resolve the dynamics of the two-phase flow. The numerical results are qualitatively validated by the experiment. Through parametric studies, we specifically examined the effects of vibration conditions (i.e., frequency and amplitude), microchannel taper angle, and wall surface contact angle (i.e., wettability) on the flow rate through the microchannel. The results will advance the potential applications where oscillatory or general unsteady microchannel two-phase flows may be present.","PeriodicalId":328276,"journal":{"name":"arXiv: Fluid Dynamics","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123679982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5