[AeroSonic]

Dear All,

I have a question regards my Solver, I have build a FORTRAN code to solve the incompressible viscous N--S equations.

at first I used dgetrf and dgetri to get the inverse of the pressure matrix and solve the pressure system by matrix multiplication.

all went well and good, after that I tried to include the PARDISO solver so I can save memory when I use a very large grid. so I am solving the pressure system by PARDISO instead of dgetrf and dgetri and matrix multiplication.


I compared the results at the first few time steps and it was identical, and tried that too at time step =100,1000,5000 and the solution was identical too. the problem appears when the time steps increases, it is like there is a cumulative error which increase with time.

my grid is 20Dx10D , Re=200, Epsilon = 0.05, dt=0.005

there is a sample of the results in attachments.
I can see the difference in numbers grows with time steps and I dont know why, although the solution was identical at the first time steps so there is no mathematical problem in the code.