[ertan]

HI, I'm working on parallelization of a 3D FVM code running on structured and (backward) staggered grid. I use domain decomposition and MPI for parallelization and fractional step for pressure. I use SIP (stones implicit method) as the solver for all variables. Data at the boundaries are exchanged via ghost cells. I exchange data at the end of each time step. The code runs well and spits out results, however, they are not the same as results from the serial code. There is a discrepancy and the pressure at the domain boundaries doesn't look smooth.

I wonder if I have to do the information exchange at every inner solver iterations? Right now, I work on that, however, I have also have some doubts about the whole picture. I guess , people prefer Multigrid method for solving pressure. I am not sure, if multigrid method is a must for parallelization. I'd like to hear some ideas from experienced people . Any resource is also welcome.

Thanks

Ertan