Hi,
I have been testing my parallel implementation with a 2D case. I have used the following grids with 2 and 4 processes: 4x4, 10x10, 16x16 and 18x18. It works for the first three (max. number of iterations to converge aprox. 70) but when I increase to 18x18 the matrix does not converge. I have increased the maximum number of iterations and I have used GMRES, BiCGSTAB with preconditioners ASM, JACOBI, etc. With KSPType = GMRES and PCType = ASM: Number of iterations: 500 Residual: +1.420471E-01 With KSPType = GMRES and PCType = JACOBI: Number of iterations: 500 Residual: +2.351882E-02 With KSPType = BCGS and PCType = ASM: Number of iterations: 136 Residual: +3.911446E+04 With KSPType = BCGS and PCType = NULL: Number of iterations: 157 Residual: +3.254728E+03 Is it normal that the convergence detiorates so much with such a slight increase in the dimension of the matrix? Is there any optimization parameter that I may be missing? Billy.
