以高超声速粘性绕流的数值模拟为例,研究LU-SGS、高斯-赛德尔点松弛、线松弛以及GMRES等隐式求解方法在空间项采用高阶精度格式WCNS离散时的收敛性,并对GMRES(generalized minimal residual)方法中的子迭代影响作了对比计算.结果表明,采用准确的解析雅克比矩阵的点、线松弛的收敛速度优于LU-SGS,以线松弛为预处理的GMRES算法具有良好的收敛特性.
With a high-order weighted compact nonlinear scheme (WCNS) for space discretization, several different implicit methods, including LU-SGS, Gauss-Seidel point-relaxation, line-relaxation and GMRES(generalized minimal residual), are compared in the simulation of hypersonic viscous flows. Both point and line relaxations with analytical Jacobian matrix converge faster than those of LU-SGS. GMRES obtains a faster convergence rate combined with line relaxation.