N-S方程组的通用形式及近似因式分解
On General Form of Navier-Stokes Equations and Implicit Factored Scheme
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摘要: 基于张量分析,本文在任意曲线坐标系中导出了用原始变量表达的Navier-Stokes(以下简称N-S)方程组弱守恒型通用形式,其中速度采用了逆变或协变分量;与将复杂的坐标变换嵌入该方程组的流行做法相比,本文所得方程组的形式简捷、直观、更适于在贴体曲线坐标系中直接求解.文中详细讨论了这个方程的因式分解过程即将一个n维流动化为n步一维问题来求解,每一步只需解一个块三对角矩阵,从而避开了大型矩阵求逆,提高了解题速度,进一步推广和发展了Beam-Warming的因式分解法.Abstract: A general weak conservative form of Navier-Stokes equations expressed with respect to non-orthogonal Curvilinear coordinates and with primitive variables was obtained by using tensor analysis technique, where the contravariant and covariant velocity components were employed. Compared with the current coordinate transformation method, the established equations are concise and forthright, and they are more convenient to be used for solving problems in body-fitted curvilinear coordinate system. An implicit factored scheme for solving the equations is presented with detailed discussions in this paper. For n-dimensional flow the algorithm requires n-steps and for each step only a block tridiagonal matrix equation needs to be solved. It avoids inverting the matrix for large systems of equations and enhances the speed of arithmetic. In this study, the Beam-Warming's implicit factored schceme is extended and developed in non-orthogonal curvilinear coordinate system.
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