About delt t in openlb code

Palabos General
#1

Hi,

My question is about the convert between physical and LB unit. When I run the multicomponent case, if the omega is too large, the result is nan. So I think I should change the deltx and delt t. I think I can change deltax by changing the lattice number, but I don’t know how to change delt t. Could you please give me some hint? Thank you very much.

Glary

#2

Hi,

To change delta_t, you need to change the velocity, as measured in lattice units (see the document “how to change lattice units”). The factor delta_t is proportional to this velocity. In a simulation with a body force (gravity), this amounts to modifying the body force.

#3

Hi,

Thank you for your reply. I have read that paper. But for the example multicomponent case, there is not velocity in the beginning, what should I do? Another question is that I use this function to conver viscosity, wheter I am right?

v_LB = v_p * delt t / deltx / deltx

omega= 1 / (3 * v_LB + 0.5 )

Thank you again!