I am currently trying to parallelize the incompressible flow solver code. However, when I run the code I realise that the parallel code takes much longer time than sequential code to finish one iteration.
The mesh is partitioned by ParMetis so the work load is balanced. I also timed my code, the main time-consuming part is the linear solver part. The method I used is the conjugate gradient and jacobi as the preconditioner from Petsc Krylov methods.
So I am wondering if there is any appropriate method and preconditioner for solving linear algebra in parallel?