position of body force on the momentum equation
 

Hi, I have a question on the position of the body force on the momentum equation. I have search the forum and find two different strategy:

1. It should be included in the Ueqn:

fvVectorMatrix UEqn ( fvm::ddt(U) + fvm::div(phi, U) - fvm::laplacian(nu, U) == F );

2: It should be included in the predictor step:

solve(UEqn ==F -fvc::grad(p));

Can any expert explain to me which one is correct?

You can do whatever you want as far as the PISO loop is consistent.

I mean, with the first option, you don't have to change anything in the algorithm (F is part of H).

For the second option, you have to modify the recontruction of the velocity from the pressure gradient to include F.

Both options leads to the same results.

Best,
Cyp

Thanks Cyp for your help.