[Peszkow]

Hello everyone!
I am creating my own solver of unsteady Stokes flow in 2D(pressure at the inlet rises linearly and stop after few seconds). At first I solve and then computed pressure is put into Stokes equations. It bases on finite difference method and uses Conjugate Gradient Method to solve the pressure equation. Next the stokes equations are solved using ADI algorithm and CGM. First step of time is okey, because the solution is zero(so it is put during initiazation). Unfortunately in next step when pressure at the inlet rises pressure don't want to converge. It is linear problem and theoritically it should converge(matrix from laplace equation is symmetricall and PDM) in some cases slowly but still it should converge. Unfortunately in my case calculations are diverging. I have checked everything but I wasn't able to find an error. Have anyone got some ideas how to find where is the problem ?