Initial conditions for airfoil in c-grid
 

hi,

I am simulating an airfoil in a flow. my solver is a fractional step non-staggered unsteady 2d NS FVM solver. I'm also using a rhie-chow interpolation.

if i set the initial conditions as u=1 throughout the c grid's cell center and u=1 at the faces of the outer boundaries cells, after about 10 time steps, I get a reasonable answer with the far field velocities around u=1.

however, if i now set u=1 at the only outer boundaries cells' center and faces, I'll set u=1.5-1.9, with bigger values at the boundaries.

May I know why this is so? In the 2nd case, I'm trying to simulate a transient condition such that the flow start from the left. Is there anything wrong?

how should the initial condition for the velocities be set and what is the basis?

thanks alot!