About gravity in Finite Volume Methods Coding
 

Hello, I am writing a FVM code and it works well without gravity. But after adding gravity terms to the momentum equations the result is wrong. I just want to simulate the pressure difference caused by gravity(hydrostatic pressure). This pressure difference will exist even the fluid is still. I know in Fluent, if I want to take it into consider, I have to set the gravity and set reference density to 0. Then what should I do with my own code? Thank you.

Give more details about your discretization, it is likely a numerical instability ..

Than you for your reply.
I get some ideas from this issue:
https://www.cfd-online.com/Forums/op...e-gravity.html
The hydrostatic pressure is not taken into consideration when we are building momentum equations. And I have to add the hydrostatic pressure from this:
p = pd + rho*g*z