hello all

If i need to perform DNS of channel flow.Let the domain be 2D Length=70 and height = 14.( these dimensions are needed for future simulation of reverse flow in channel).

Re based on the height is 3,64,000.What should be grid size .I have seen the literature but not clear.can any one help. thanx Senthil.

DNS in 2D doesn't mean a lot in real world. Anyway, if L is the size of your domain and eta is the grid size, then you have the following relation :

Number of cells = (L/eta)^3 = (Re_t)^(9/4)

where Re_t is the turbulent Reynolds number :

Re_t = sqrt(k) l / nu ) = k^2 / ( nu epsilon )

k = turbulent kinetic energy;

l = integral length scale;

epsilon = dissipation rate;

nu = viscosity.

Hope that helps

Sylvain