[harbinyg]

Hi,


I currently meet some problems with the implementaion of the periodic boundary condition for transient Rayleigh-Benard convection problem.


My code is based on FVM, SIMPLE algorithm and colocatted grid system (with Rhie-Chow interpolation) .

i am prettly sure that my code works for adiabtic boundary condition for temperature (no-slip wall for velocities), as i compared my results with some beachmark solutions.

To simulate a infinite long domain in horizontal direction (my solver is two - dimensional), i want to implment periodic boundary condition for temperature, velocity and pressure fields.

Thus i did some modification of the code,

for tempearture and velocity field, i exchange the values on boundaries, like (a N by N grid )
phi(1, j) = phi(N-1,j)
phi(N,j) = phi(2,j)
then treat the boundary type like Dirichlet condition;

for pressure field,

at the beginning i think we may not need any modification as the problem i considered is not like the other type periodic boundary condition , like there is a incomming flow and we need to guarantee the constant pressure drop.

then i realized that the pressure correction genearlly implicitly incoperates with Neumann boundaries for all boundaries, then i did some modification like temperature field.

However, i failed, as the solver directly divergence in the first two or three time steps and i do not know the reason. I wish someone who has similar experience can help me.

If someone can provide some usful materials, it would be great.