A critical evaluation of upstream differencing applied to problems involving fluid flow
A critical evaluation of upstream differencing applied to problems involving fluid flow
复制标题
应用于流体流动问题的上游差分的关键评估
DOI：
10.1016/0045-7825(76)90078-5
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发表时间：
1976
期刊：
影响因子：
--
通讯作者：
G. Raithby
中科院分区：
文献类型：
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作者：
G. Raithby
在近似守恒方程中的对流项时，有时使用上游差分。然而，反对意见，部分基于虚假或数字扩散的出现，经常被提出。本文表明，通常与上游差异相关的假扩散是近似对流项总误差的一个较差指标，并提出了假扩散的新定义。然后确定上游近似有效的极限条件；进行了几个数值实验，以确定在上游近似导致不可接受的误差之前，人们可能偏离这些理想条件的程度。结论是，上游近似仅在有限条件下有效，但这些条件包括许多实际问题。
In approximating the convection terms in conservation equations, upstream differences are sometimes used. However, objections, based partly on the appearance of a false or numerical diffusion, are often raised. This paper shows that the false diffusion normally associated with upstream differences is a poor indicator of the total error in approximating the convection terms, and a new definition for false diffusion is proposed. The limiting conditions under which the upstream approximation is valid are then determined; several numerical experiments are performed to determine how much one may depart from these ideal conditions before the upstream approximation leads to unacceptable errors. It is concluded that the upstream approximation is valid only under restricted conditions, but that these include many problems of practical interest.