Theoretical and Computational Fluid Dynamics最新文献_第10页

Optimal computational parameters for maximum accuracy and minimum cost of Arnoldi-based time-stepping methods for flow global stability analysis 基于arnoldi的流场全局稳定性分析时步法的最优计算参数，以获得最大精度和最小代价

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2022-11-06 DOI: 10.1007/s00162-022-00634-x

Marlon Sproesser Mathias, Marcello Augusto Faraco de Medeiros

{"title":"Optimal computational parameters for maximum accuracy and minimum cost of Arnoldi-based time-stepping methods for flow global stability analysis","authors":"Marlon Sproesser Mathias, Marcello Augusto Faraco de Medeiros","doi":"10.1007/s00162-022-00634-x","DOIUrl":"10.1007/s00162-022-00634-x","url":null,"abstract":"<div>Global instability analysis of flows is often performed via time-stepping methods, based on the Arnoldi algorithm. When setting up these methods, several computational parameters must be chosen, which affect intrinsic errors of the procedure, such as the truncation errors, the discretization error of the flow solver, the error associated with the nonlinear terms of the Navier–Stokes equations and the error associated with the limited size of the approximation of the Jacobian matrix. This paper develops theoretical equations for the estimation of optimal balance between accuracy and cost for each case. The 2D open cavity flow is used both for explaining the effect of the parameters on the accuracy and the cost of the solution, and for verifying the quality of the predictions. The equations demonstrate the impact of each parameter on the quality of the solution. For example, if higher-order methods are used for approaching a Fréchet derivative in the procedure, it is shown that the solution deteriorates more rapidly for larger grids or less accurate flow solvers. On the other hand, lower-order approximations are more sensitive to the initial disturbance magnitude. Nevertheless, for accurate flow solvers and moderate grid dimensions, first-order Fréchet derivative approximation with optimal computational parameters can provide 5 decimal place accurate eigenvalues. It is further shown that optimal parameters based on accuracy tend to also lead to the most cost-effective solution. The predictive equations, guidelines and conclusions are general, and, in principle, applicable to any flow, including 3D ones.</div>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"36 6","pages":"1013 - 1036"},"PeriodicalIF":3.4,"publicationDate":"2022-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00162-022-00634-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4271929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Dispersion of free-falling saliva droplets by two-dimensional vortical flows 自由落体唾液滴在二维涡旋流中的分散

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2022-11-05 DOI: 10.1007/s00162-022-00633-y

Orr Avni, Yuval Dagan

{"title":"Dispersion of free-falling saliva droplets by two-dimensional vortical flows","authors":"Orr Avni, Yuval Dagan","doi":"10.1007/s00162-022-00633-y","DOIUrl":"10.1007/s00162-022-00633-y","url":null,"abstract":"The dispersion of respiratory saliva droplets by indoor wake structures may enhance the transmission of various infectious diseases, as the wake spreads virus-laden droplets across the room. Thus, this study analyzes the interaction between vortical wake structures and exhaled multi-component saliva droplets. A self-propelling analytically described dipolar vortex is chosen as a model wake flow, passing through a cloud of micron-sized evaporating saliva droplets. The droplets’ spatial location, velocity, diameter, and temperature are traced, coupled to their local flow field. For the first time, the wake structure decay is incorporated and analyzed, which is proved essential for accurately predicting the settling distances of the dispersed droplets. The model also considers the nonvolatile saliva components, adequately capturing the essence of droplet–aerosol transition and predicting the equilibrium diameter of the residual aerosols. Our analytic model reveals non-intuitive interactions between wake flows, droplet relaxation time, gravity, and transport phenomena. We reveal that given the right conditions, a virus-laden saliva droplet might translate to distances two orders of magnitude larger than the carrier-flow characteristic size. Moreover, accounting for the nonvolatile contents inside the droplet may lead to fundamentally different dispersion and settling behavior compared to non-evaporating particles or pure water droplets. Ergo, we suggest that the implementation of more complex evaporation models might be critical in high-fidelity simulations aspiring to assess the spread of airborne respiratory droplets.","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"36 6","pages":"993 - 1011"},"PeriodicalIF":3.4,"publicationDate":"2022-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00162-022-00633-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4225078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Three-dimensional evolution of body and fluid motion near a wall 物体的三维演化和壁面附近的流体运动

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2022-10-30 DOI: 10.1007/s00162-022-00631-0

Frank T. Smith, Kevin Liu

引用次数: 1

LBM study of natural convection heat transfer from a porous cylinder in an enclosure 自然对流换热的LBM研究

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2022-10-28 DOI: 10.1007/s00162-022-00632-z

B. Shruti, Md. Mahbub Alam, A. Parkash, S. Dhinakaran

{"title":"LBM study of natural convection heat transfer from a porous cylinder in an enclosure","authors":"B. Shruti, Md. Mahbub Alam, A. Parkash, S. Dhinakaran","doi":"10.1007/s00162-022-00632-z","DOIUrl":"10.1007/s00162-022-00632-z","url":null,"abstract":"Natural convection heat transfer from a porous cylinder put at various positions in a square, cooled enclosure, with air as the working fluid, is investigated in this work. The following setups are taken into account: The hot cylinder is placed in the middle of the enclosure, near the bottom, top, right sides, along diagonal as top-diagonal and bottom-diagonal. The cylinder and the enclosure walls are kept hot and cold, respectively. The lattice Boltzmann method is used to perform a numerical analysis for Rayleigh number (10^{4}le ) Ra (le 10^{6}) and Darcy number (10^{-6}le ) Da (le 10^{-2}). The results are plotted as streamlines, isotherms, and local and mean Nusselt number values. The amount of heat transported from the heated porous cylinder is determined by varying Ra, Da, and the cylinder location. Even at a lower Rayleigh number ((10^{4})), the average Nusselt number grows by nearly 70 % as the cylinder moves from the centre to the bottom and 105% as it moves to bottom-diagonal location when ({Da}=10^{-2}). At Ra (=10^{6}) and Da (=10^{-2}), the heat transfer rate of the cylinder located near the corner of the enclosure at the bottom wall increases by approximately 33% when compared to the case of the cylinder in the centre. Convective effects are more noticeable when the cylinder is positioned towards the enclosure’s bottom wall. This research is applicable to electronic cooling applications in which a collection of electronic components is arranged in a circular pattern inside a cabinet.","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"36 6","pages":"943 - 967"},"PeriodicalIF":3.4,"publicationDate":"2022-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00162-022-00632-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5580682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

VOF with center of mass and Lagrangian particles (VCLP): a surface tracking and advection method for incompressible fluids 具有质心和拉格朗日粒子的VOF (VCLP):一种不可压缩流体表面跟踪和平流方法

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2022-10-16 DOI: 10.1007/s00162-022-00628-9

Richards C Sunny, Juan Horrillo, Wei Cheng

{"title":"VOF with center of mass and Lagrangian particles (VCLP): a surface tracking and advection method for incompressible fluids","authors":"Richards C Sunny, Juan Horrillo, Wei Cheng","doi":"10.1007/s00162-022-00628-9","DOIUrl":"10.1007/s00162-022-00628-9","url":null,"abstract":"A novel surface tracking, and advection algorithm for incompressible fluid flows in two and three dimensions is presented. This method based on the volume-of-fluid (VOF) method, is named VOF-with-center-of-mass-and-Lagrangian-particles (VCLP), and it uses spatially and temporally localized Lagrangian particles (LPs) inside a finite volume framework. The fluid surface is recaptured and reconstructed piecewise using the mean slope and curvature. The fluid mass inside each cell is discretized spatially by LPs and distributed as blue noise. LPs are then advected cell by cell with a choice of two different advection schemes in time using interpolated velocity and approximated acceleration fields. VCLP continuously tracks the center of mass of the fluid parcels in the Lagrangian way and this helps to reduce the errors due to numerical acceleration that results from lack of information to reconstruct the interface accurately. VCLP’s performance is evaluated using standard benchmark tests in 2D and 3D such as translation, single vortex, deformation, and Zalesak’s tests from the literature. VCLP is applied to TSUNAMI2D, a 2D Navier–Stokes model to simulate shoaling and breaking of waves.","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"36 6","pages":"915 - 942"},"PeriodicalIF":3.4,"publicationDate":"2022-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4661438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Solutions to aliasing in time-resolved flow data 解决时间分辨流数据中的混叠问题

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2022-10-11 DOI: 10.1007/s00162-022-00630-1

Ugur Karban, Eduardo Martini, Peter Jordan, Guillaume A. Brès, Aaron Towne

{"title":"Solutions to aliasing in time-resolved flow data","authors":"Ugur Karban, Eduardo Martini, Peter Jordan, Guillaume A. Brès, Aaron Towne","doi":"10.1007/s00162-022-00630-1","DOIUrl":"10.1007/s00162-022-00630-1","url":null,"abstract":"Avoiding aliasing in time-resolved flow data obtained through high-fidelity simulations while keeping the computational and storage costs at acceptable levels is often a challenge. Well-established solutions such as increasing the sampling rate or low-pass filtering to reduce aliasing can be prohibitively expensive for large datasets. This paper provides a set of alternative strategies for identifying and mitigating aliasing that are applicable even to large datasets. We show how time-derivative data, which can be obtained directly from the governing equations, can be used to detect aliasing and to turn the ill-posed problem of removing aliasing from data into a well-posed problem, yielding a prediction of the true spectrum. Similarly, we show how spatial filtering can be used to remove aliasing for convective systems. We also propose strategies to prevent aliasing when generating a database, including a method tailored for computing nonlinear forcing terms that arise within the resolvent framework. These methods are demonstrated using a nonlinear Ginzburg–Landau model and large-eddy simulation data for a subsonic turbulent jet.","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"36 6","pages":"887 - 914"},"PeriodicalIF":3.4,"publicationDate":"2022-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4477096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

A specific slip length model for the Maxwell slip boundary conditions in the Navier–Stokes solution of flow around a microparticle in the no-slip and slip flow regimes 无滑移和滑移两种流动状态下微粒周围流动的Navier-Stokes解麦克斯韦滑移边界条件的特定滑移长度模型

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2022-09-07 DOI: 10.1007/s00162-022-00627-w

Jana Wedel, Mitja Štrakl, Jure Ravnik, Paul Steinmann, Matjaž Hriberšek

{"title":"A specific slip length model for the Maxwell slip boundary conditions in the Navier–Stokes solution of flow around a microparticle in the no-slip and slip flow regimes","authors":"Jana Wedel, Mitja Štrakl, Jure Ravnik, Paul Steinmann, Matjaž Hriberšek","doi":"10.1007/s00162-022-00627-w","DOIUrl":"10.1007/s00162-022-00627-w","url":null,"abstract":"In the case of microscopic particles, the momentum exchange between the particle and the gas flow starts to deviate from the standard macroscopic particle case, i.e. the no-slip case, with slip flow occurring in the case of low to moderate particle Knudsen numbers. In order to derive new drag force models that are valid also in the slip flow regime for the case of non-spherical particles of arbitrary shapes using computational fluid dynamics, the no-slip conditions at the particle surface have to be modified in order to account for the velocity slip at the surface, mostly in the form of the Maxwell’s slip model. To allow a continuous transition in the boundary condition at the wall from the no-slip case to the slip cases for various Knudsen (Kn) number value flow regimes, a novel specific slip length model for the use with the Maxwell boundary conditions is proposed. The model is derived based on the data from the published experimental studies on spherical microparticle drag force correlations and Cunningham-based slip correction factors at standard conditions and uses a detailed CFD study on microparticle fluid dynamics to determine the correct values of the specific slip length at selected Kn number conditions. The obtained data on specific slip length are correlated using a polynomial function, resulting in the specific slip length model for the no-slip and slip flow regimes that can be applied to arbitrary convex particle shapes.","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"36 5","pages":"723 - 740"},"PeriodicalIF":3.4,"publicationDate":"2022-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00162-022-00627-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4322313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Acoustic receptivity of high-speed boundary layers on a flat plate at angles of attack 攻角下平板上高速边界层的声接受度

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2022-08-30 DOI: 10.1007/s00162-022-00625-y

Alexander V. Fedorov, Natalia Palchekovskaya

{"title":"Acoustic receptivity of high-speed boundary layers on a flat plate at angles of attack","authors":"Alexander V. Fedorov, Natalia Palchekovskaya","doi":"10.1007/s00162-022-00625-y","DOIUrl":"10.1007/s00162-022-00625-y","url":null,"abstract":"Direct numerical simulation and theoretical analysis of acoustic receptivity are performed for the boundary layer on a flat plate in Mach 6 flow at various angles of attack (AoA). Slow or fast acoustic wave passes through: a bow shock at AoA (=-5^{circ }), a weak shock induced by the viscous–inviscid interaction at AoA (=0^{circ }) or an expansion fan emanating from the plate leading edge at AoA (=5^{circ }). The study is focused on cases where the integral amplification of unstable mode S (or Mack second mode) is sufficiently large ((Napprox 8.4)) to be relevant to transition in low-disturbance environments. It is shown that excitation of dominant modes F and S occurs in a small vicinity of the plate leading edge. The initial disturbance propagates further downstream in accord with the two-mode approximation model accounting for the mean-flow nonparallel effects and the intermodal exchange mechanism. This computationally economical model can be useful for predictions of the second mode dominated transition onset using the physics-based amplitude method.\u0000","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"36 5","pages":"705 - 722"},"PeriodicalIF":3.4,"publicationDate":"2022-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4002736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Spectral proper orthogonal decomposition using multitaper estimates 利用多锥度估计的光谱固有正交分解

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2022-08-27 DOI: 10.1007/s00162-022-00626-x

Oliver T. Schmidt

引用次数: 10

Numerical tripping of high-speed turbulent boundary layers 高速湍流边界层的数值脱扣

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2022-08-11 DOI: 10.1007/s00162-022-00623-0

Alessandro Ceci, Andrea Palumbo, Johan Larsson, Sergio Pirozzoli

{"title":"Numerical tripping of high-speed turbulent boundary layers","authors":"Alessandro Ceci, Andrea Palumbo, Johan Larsson, Sergio Pirozzoli","doi":"10.1007/s00162-022-00623-0","DOIUrl":"10.1007/s00162-022-00623-0","url":null,"abstract":"The influence of turbulence inflow generation on direct numerical simulations (DNS) of high-speed turbulent boundary layers at Mach numbers of 2 and 5.84 is investigated. Two main classes of inflow conditions are considered, based on the recycling/rescaling (RR) and the digital filtering (DF) approach, along with suitably modified versions. A series of DNS using very long streamwise domains is first carried out to provide reliable data for the subsequent investigation. A set of diagnostic parameters is then selected to verify achievement of an equilibrium state, and correlation laws for those quantities are obtained based on benchmark cases. Simulations using shorter domains, with extent comparable with that used in the current literature, are then carried out and compared with the benchmark data. Significant deviations from equilibrium conditions are found, to a different extent for the various flow properties, and depending on the inflow turbulence seeding. We find that the RR method yields superior performance in the evaluation of the inner-scaled wall pressure fluctuations and the turbulent shear stress. DF methods instead yield quicker adjustment and better accuracy in the prediction of wall friction and of the streamwise Reynolds stress in supersonic cases. Unrealistically high values of the wall pressure variance are obtained by the baseline DF method, while the proposed DF alternatives recover a closer agreement with respect to the benchmark. The hypersonic test case highlights that similar distribution of wall friction and heat transfer are obtained by both RR and DF baseline methods.","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"36 6","pages":"865 - 886"},"PeriodicalIF":3.4,"publicationDate":"2022-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00162-022-00623-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4442531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 8