Computers & Fluids最新文献_第3页

Using lateral dispersion to optimise microfluidic trap array efficiency 利用横向色散优化微流体阱阵列效率

IF 2.5 3区工程技术

Computers & Fluids Pub Date : 2025-04-30 DOI: 10.1016/j.compfluid.2025.106643

Nicolas Ruyssen , Gabriel Fina , Rachele Allena , Marie-Caroline Jullien , Jacques Fattaccioli

{"title":"Using lateral dispersion to optimise microfluidic trap array efficiency","authors":"Nicolas Ruyssen , Gabriel Fina , Rachele Allena , Marie-Caroline Jullien , Jacques Fattaccioli","doi":"10.1016/j.compfluid.2025.106643","DOIUrl":"10.1016/j.compfluid.2025.106643","url":null,"abstract":"<div><div>Microfluidic trapping arrays have proven to be efficient tools for various applications that require working at the single-cell level, such as cell–cell communication or fusion. Although several hydrodynamic trapping devices have already been optimised, two-dimensional (2D) single-layer trapping arrays with high trap densities remain partially inefficient. Specifically, many traps remain empty, even after prolonged injection, which drastically reduces the number of samples available for post-treatment. These unfilled traps result from the symmetrical nature of the flow around the traps, and breaking this symmetry enhances capture efficiency. In this study, we use a numerical approach to show that optimal geometries can significantly increase filling efficiency and a preliminary experimental test confirming our approach is provided. We show that these improvements are achieved by promoting lateral dispersion of particles, facilitated either through an optimised oblique flow or by introducing disorder into the spatial arrangement of traps without specific inlet/outlet adjustment.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"297 ","pages":"Article 106643"},"PeriodicalIF":2.5,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143931515","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

Approximate well-balanced WENO finite difference schemes using a global-flux quadrature method with multi-step ODE integrator weights 利用多步ODE积分器权值的全局通量积分法近似平衡WENO有限差分格式

IF 2.5 3区工程技术

Computers & Fluids Pub Date : 2025-04-28 DOI: 10.1016/j.compfluid.2025.106646

M. Kazolea , C. Parés , M. Ricchiuto

{"title":"Approximate well-balanced WENO finite difference schemes using a global-flux quadrature method with multi-step ODE integrator weights","authors":"M. Kazolea , C. Parés , M. Ricchiuto","doi":"10.1016/j.compfluid.2025.106646","DOIUrl":"10.1016/j.compfluid.2025.106646","url":null,"abstract":"<div><div>In this work, high-order discrete well-balanced methods for one-dimensional hyperbolic systems of balance laws are proposed. We aim to construct a method whose discrete steady states correspond to solutions of arbitrary high-order ODE integrators. However, this property is embedded directly into the scheme, eliminating the need to apply the ODE integrator explicitly to solve the local Cauchy problem.</div><div>To achieve this, we employ a WENO finite difference framework and apply WENO reconstruction to a global flux assembled nodewise as the sum of the physical flux and a source primitive. The novel idea is to compute the source primitive using high-order multi-step ODE methods applied on the finite difference grid. This approach provides a locally well-balanced splitting of the source integral, with weights derived from the ODE integrator. By construction, the discrete solutions of the proposed schemes align with those of the underlying ODE integrator.</div><div>The proposed methods employ WENO flux reconstructions of varying orders, combined with multi-step ODE methods of up to order 8, achieving steady-state accuracy determined solely by the ODE method’s consistency. Numerical experiments using scalar balance laws and shallow water equations confirm that the methods achieve optimal convergence for time-dependent solutions and significant error reduction for steady-state solutions.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"296 ","pages":"Article 106646"},"PeriodicalIF":2.5,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143887631","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

Novel finite volume method with Walsh basis function and its multigrid features 基于Walsh基函数的有限体积法及其多网格特征

IF 2.5 3区工程技术

Computers & Fluids Pub Date : 2025-04-28 DOI: 10.1016/j.compfluid.2025.106663

Yuan Gan , Gang Wang , Jiong Ren

{"title":"Novel finite volume method with Walsh basis function and its multigrid features","authors":"Yuan Gan , Gang Wang , Jiong Ren","doi":"10.1016/j.compfluid.2025.106663","DOIUrl":"10.1016/j.compfluid.2025.106663","url":null,"abstract":"<div><div>In previous work, the authors published a novel numerical method capable of capturing discontinuities (e.g., shock waves) for 1D problems within the grid cell (Ren & Wang, 2020), which is called the Finite Volume Method with Walsh Basis Functions (FVM-WBF). In the FVM-WBF method, the conservative variables within a grid cell are expressed in the expansion form of the WBF series. By extending this series, the accuracy of capturing discontinuities can be significantly improved. However, this method does result in a significant increase in computational cost, especially for high-dimensional problems. In this paper, the FVM-WBF method is extended to 2D and 3D cases. Additionally, to address the efficiency issues, an innovative multigrid approach is proposed to enhance the computational efficiency of this method. Following an analysis of the WBFs, it was found that there are spatial scales in the expression of different WBF series within the grid cell, which is similar to different grid levels in <em>h</em>-multigrid method. Based on this finding, a simple and efficient multigrid algorithm is devised and implemented in the FVM-WBF method. This multigrid algorithm has advantages over the classical <em>h</em>-multigrid implementation in that it does not require interpolation/constraint operators or transferring information between different grid hierarchies, and the computational efficiency can be significantly improved only by adopting the time step size based on spatial scales without increasing the computational cost at each iteration. Several test cases are presented and the results show that the computational efficiency of the proposed method can be effectively improved.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"297 ","pages":"Article 106663"},"PeriodicalIF":2.5,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143907006","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

Achieving rapid convergence in false-transient RANS simulations on unstructured meshes using an implicit adaptive time stepping method 采用隐式自适应时间步进方法实现非结构化网格上伪瞬态RANS仿真的快速收敛

IF 2.5 3区工程技术

Computers & Fluids Pub Date : 2025-04-26 DOI: 10.1016/j.compfluid.2025.106644

M.R. Nived , Nikhil Narayan Kalkote , Vinayak Eswaran

{"title":"Achieving rapid convergence in false-transient RANS simulations on unstructured meshes using an implicit adaptive time stepping method","authors":"M.R. Nived , Nikhil Narayan Kalkote , Vinayak Eswaran","doi":"10.1016/j.compfluid.2025.106644","DOIUrl":"10.1016/j.compfluid.2025.106644","url":null,"abstract":"<div><div>A variable time-step algorithm based on the second-order backward differentiation formula (BDF2) for rapidly changing time steps is applied to false-transient simulations of stationary turbulent flow solutions to obtain rapid convergence to steady-state. This adaptive time stepping (ATS) algorithm imposes a user-defined tolerance limit on the local truncation error to estimate the maximum allowable time-step size for pseudo-time marching. It can be readily integrated into any pre-existing implicit flow solver. The algorithm is incorporated into a parallel implicit compressible flow solver that uses the block LUSGS method to compute solutions of linear systems on unstructured grids. The ATS solver is verified using test cases of incompressible flow over a flat plate and a NACA-0012 airfoil near stall to showcase its capability to produce rapid convergence to machine precision even on high aspect ratio meshes. The ATS algorithm reduces overall simulation times by factors of 100-200 times compared to constant CFL time-stepping, even in the case of transonic flow over an <em>Onera M6</em> wing. Its performance against a few basic CFL laws is also shown to be good and a thorough comparison with competing methods will be undertaken later. The adaptive implicit algorithm is also deployed to simulate transonic flow over a <em>DLR-F6</em> aircraft wing body configuration with/without nacelle and pylon, demonstrating its application in practical aircraft design.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"296 ","pages":"Article 106644"},"PeriodicalIF":2.5,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143892038","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

A positivity-preserving approach for implicit dual-time stepping schemes in multi-component flow simulations 多分量流模拟中隐式双时间步进格式的保正性方法

IF 2.5 3区工程技术

Computers & Fluids Pub Date : 2025-04-25 DOI: 10.1016/j.compfluid.2025.106629

Hongmin Su, Pengxin Liu, Xianxu Yuan, Bo Li, Qilong Guo

{"title":"A positivity-preserving approach for implicit dual-time stepping schemes in multi-component flow simulations","authors":"Hongmin Su, Pengxin Liu, Xianxu Yuan, Bo Li, Qilong Guo","doi":"10.1016/j.compfluid.2025.106629","DOIUrl":"10.1016/j.compfluid.2025.106629","url":null,"abstract":"<div><div>The implicit dual-time stepping schemes are very efficient in solving the multi-component flows with a time scale discrepancy induced by the chemical reactions. However, high-order accurate simulations often fail to obtain a converged result due to non-positive density or pressure during computations. In this paper, we deduce a sufficient condition for positivity-preserving of the dual-time stepping scheme with explicit pseudo-time and implicit physical time stepping, which allows a simple and efficient positivity-preserving flux limiter by the weight average of Lax–Friedrichs and high-order numerical fluxes. This flux limiter requires less time restriction than the earlier positivity-preserving strategy, implying a higher computational efficiency. In addition, it only introduces minor changes in the eigenvalues for the high-order numerical fluxes when projected to conservative variables, retaining the accuracy of the numerical fluxes to the greatest extent possible. This approach can be applied equally to the implicit dual-time stepping scheme because the solution will be positivity-preserving when converged sufficiently. Various validations computed by the fifth-order WENOZ and second-order Runge–Kutta scheme indicate that the present positivity-preserving algorithm possesses an excellent capability of simulating multi-component flows with strong discontinuities accurately and efficiently.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"297 ","pages":"Article 106629"},"PeriodicalIF":2.5,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143928207","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

Structure-preserving nonstaggered central schemes for the multidimensional Ripa system 多维Ripa系统的结构保持非交错中心方案

IF 2.5 3区工程技术

Computers & Fluids Pub Date : 2025-04-25 DOI: 10.1016/j.compfluid.2025.106639

Jian Dong , Xu Qian , Songhe Song

{"title":"Structure-preserving nonstaggered central schemes for the multidimensional Ripa system","authors":"Jian Dong , Xu Qian , Songhe Song","doi":"10.1016/j.compfluid.2025.106639","DOIUrl":"10.1016/j.compfluid.2025.106639","url":null,"abstract":"<div><div>The main difference between the usual shallow water equation and the Ripa system lies in the definitions of their steady states. Although the shallow water equation and the Ripa system are very similar, it is challenging to retain the steady states of the Ripa system, which admits more complex steady states, such as the isobaric steady state and the constant depth steady state. We introduce a nonstaggered central scheme to preserve all the steady states of the Ripa system. We use a path-conservative method to discretize the source term to maintain the still-water steady state with a constant temperature. To retain the isobaric and constant depth steady states, we introduce a steady-state-preserving parameter to modify the backward step. The moving-water equilibria are preserved by constructing equilibrium variables instead of conservative variables, along with a carefully discretized source term. We prove that the current scheme is convergent based on a path-conservative discretization of the source term. Additionally, we rigorously prove that the proposed numerical scheme guarantees that both the temperature and water depth remain nonnegative. We also extend the approach to multidimensional nonstaggered central schemes for the multidimensional Ripa system. Finally, various one- and two-dimensional numerical simulations of classical problems from the Ripa system are conducted to verify the properties of the nonstaggered central scheme.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"296 ","pages":"Article 106639"},"PeriodicalIF":2.5,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143892037","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

Reentry aerothermodynamic analysis of a high-speed vehicle with coupled ablating surface interface effects at rarefied conditions 稀薄条件下具有耦合烧蚀面界面效应的高速飞行器再入气动热力学分析

IF 2.5 3区工程技术

Computers & Fluids Pub Date : 2025-04-22 DOI: 10.1016/j.compfluid.2025.106637

Ahilan Appar , Rakesh Kumar

{"title":"Reentry aerothermodynamic analysis of a high-speed vehicle with coupled ablating surface interface effects at rarefied conditions","authors":"Ahilan Appar , Rakesh Kumar","doi":"10.1016/j.compfluid.2025.106637","DOIUrl":"10.1016/j.compfluid.2025.106637","url":null,"abstract":"<div><div>This study presents a conjugate flow-thermal analysis of a hypersonic reentry vehicle in rarefied flow conditions, along with a stability analysis for the coupled ablation problem, highlighting additional time-step stability criteria. A novel coupling of an in-house Direct Simulation Monte Carlo (DSMC) solver with a material thermal response (MTR) solver is used. The DSMC solver is extended to simulate the physical injection of transpiring pyrolysis gas into the gas-surface interface, modeled as surface jets. The MTR code solves heat conduction in a two-dimensional/axisymmetric geometry, accounting for complex thermochemical processes, including endothermic pyrolysis, transpiration cooling and surface recession due to thermal ablation. The DSMC and MTR solvers are loosely coupled at selected time intervals (anchor points) along the reentry trajectory, exchanging boundary conditions at the fluid–solid interface. A code-to-code comparison with the well-established open-source DSMC solver, SPARTA, shows good agreement with the in-house mass-injecting DSMC framework. The results highlight the importance of the coupled DSMC-MTR framework for accurately modeling the interaction between flow and thermal domains, which is crucial in rarefied flows and for curved geometries, areas where empirical models, such as blowing effect correlation, show large deviations. Unlike the traditional empirical correlation, the DSMC framework captures the physical transpiring boundary, significantly improving flow simulations. The study also reveals that while the iterative coupling method provides accurate results, it becomes prohibitively expensive at lower altitudes, while the non-iterative method becomes unstable below 90 km. This limitation underscores the need for more sophisticated models at the gas-surface interface, particularly for transpiring boundaries, to better capture the complex interactions in hypersonic flows.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"295 ","pages":"Article 106637"},"PeriodicalIF":2.5,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143864900","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

Entropy-conservative high-order methods for high-enthalpy gas flows 高焓气体流动的熵保守高阶方法

IF 2.5 3区工程技术

Computers & Fluids Pub Date : 2025-04-22 DOI: 10.1016/j.compfluid.2025.106640

Georgii Oblapenko, Manuel Torrilhon

引用次数: 0

A comparative analysis of mesh-based and particle-based numerical methods for landslide run-out simulations 基于网格和基于粒子的滑坡失控模拟数值方法比较分析

IF 2.5 3区工程技术

Computers & Fluids Pub Date : 2025-04-21 DOI: 10.1016/j.compfluid.2025.106641

Marco Fois , Federico Gatti , Carlo de Falco , Luca Formaggia

{"title":"A comparative analysis of mesh-based and particle-based numerical methods for landslide run-out simulations","authors":"Marco Fois , Federico Gatti , Carlo de Falco , Luca Formaggia","doi":"10.1016/j.compfluid.2025.106641","DOIUrl":"10.1016/j.compfluid.2025.106641","url":null,"abstract":"<div><div>Landslides are among the most dangerous natural disasters, with their unpredictability and potential for catastrophic human and economic losses exacerbated by climate change. Continuous monitoring and precise modeling of landslide-prone areas are crucial for effective risk management and mitigation. This study explores two distinct numerical simulation approaches: the mesh-based finite element model and the particle-based model. Both methods are analyzed for their ability to simulate landslide dynamics, focusing on their respective advantages in handling complex terrain, material interactions, and large deformations. A modified version of the second-order Taylor-Galerkin scheme and the depth-averaged Material Point Method are employed to model gravity-driven free surface flows, based on depth-integrated incompressible Navier–Stokes equations. The methods are rigorously tested against benchmarks and applied to a real-world scenario to assess their performance, strengths, and limitations. The results offer insights into selecting appropriate simulation techniques for landslide analysis, depending on specific modeling requirements and computational resources.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"295 ","pages":"Article 106641"},"PeriodicalIF":2.5,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143859575","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

General field evaluation in high-order meshes on GPUs 在gpu上进行高阶网格的一般现场评估

IF 2.5 3区工程技术

Computers & Fluids Pub Date : 2025-04-19 DOI: 10.1016/j.compfluid.2025.106606

Ketan Mittal , Aditya Parik , Som Dutta , Paul Fischer , Tzanio Kolev , James Lottes

{"title":"General field evaluation in high-order meshes on GPUs","authors":"Ketan Mittal , Aditya Parik , Som Dutta , Paul Fischer , Tzanio Kolev , James Lottes","doi":"10.1016/j.compfluid.2025.106606","DOIUrl":"10.1016/j.compfluid.2025.106606","url":null,"abstract":"<div><div>Robust and scalable function evaluation at any arbitrary point in the finite/spectral element mesh is required for querying the partial differential equation solution at points of interest, comparison of solution between different meshes, and Lagrangian particle tracking. This is a challenging problem, particularly for high-order unstructured meshes partitioned in parallel with MPI, as it requires identifying the element that overlaps a given point and computing the corresponding reference space coordinates. We present a robust and efficient technique for general field evaluation in large-scale high-order meshes with quadrilaterals and hexahedra. In the proposed method, a combination of globally partitioned and processor-local maps are used to first determine a list of candidate MPI ranks, and then locally candidate elements that could contain a given point. Next, element-wise bounding boxes further reduce the list of candidate elements. Finally, Newton’s method with trust region is used to determine the overlapping element and corresponding reference space coordinates. Since GPU-based architectures have become popular for accelerating computational analyses using meshes with tensor-product elements, specialized kernels have been developed to utilize the proposed methodology on GPUs. The method is also extended to enable general field evaluation on surface meshes. The paper concludes by demonstrating the use of the proposed method in various applications ranging from mesh-to-mesh transfer during r-adaptivity to Lagrangian particle tracking.</div></div>","PeriodicalId":287,"journal":{"name":"Computers & Fluids","volume":"295 ","pages":"Article 106606"},"PeriodicalIF":2.5,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143864899","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