LS‐DYNA and the 8:1 differentially heated cavity
LS‐DYNA and the 8:1 differentially heated cavity
复制标题
LS-DYNA 和 8:1 差热腔
DOI：
10.1002/fld.400
复制
发表时间：
2002
期刊：
影响因子：
--
通讯作者：
M. Christon
中科院分区：
文献类型：
--
作者：
M. Christon
本文介绍了使用LS-DYNA新的不可压缩流求解器在略超临界Rayleigh数下对长宽比为8：1的差热空腔进行计算的结果。三种基于Galerkin的求解方法应用于8：1热腔的四个网格序列。求解方法包括显式时间积分算法和两种二阶投影方法-半隐式和全隐式。对基本Galerkin有限元法的一系列特别修改导致解质量下降，其中最严重的影响是由行和集中质量矩阵引入的。集中质量矩阵相对于一致质量矩阵的较差精度用显式算法证明，显式算法未能在粗网格上获得瞬态解，并且表现出低估预测振荡幅度的总体趋势。半隐式和全隐式二阶投影方法可以获得最佳结果，其中全隐式方法与“智能”时间积分器结合使用。版权所有© 2002年约翰威利父子有限公司。
This paper presents results computed using LS‐DYNA's new incompressible flow solver for a differentially heated cavity with an 8:1 aspect ratio at a slightly super‐critical Rayleigh number. Three Galerkin‐based solution methods are applied to the 8:1 thermal cavity on a sequence of four grids. The solution methods include an explicit time‐integration algorithm and two second‐order projection methods—one semi‐implicit and the other fully implicit. A series of ad hoc modifications to the basic Galerkin finite element method are shown to result in degraded solution quality with the most serious effects introduced by row‐sum lumping the mass matrix. The inferior accuracy of a lumped mass matrix relative to a consistent mass matrix is demonstrated with the explicit algorithm which fails to obtain a transient solution on the coarsest grid and exhibits a general trend to under‐predict oscillation amplitudes. The best results are obtained with semi‐implicit and fully implicit second‐order projection methods where the fully implicit method is used in conjunction with a ‘smart’ time integrator. Copyright © 2002 John Wiley & Sons, Ltd.