[Nicolas Freuville]

Hi everyone,
I'm a newbie with Fluent and I've to simulate a flow in a chamber with compressive gas and slow motion (a few mm/s).
I made a simulation with the "pressure based" model and another with the "density based" model. I see some velocity difference (~5%) between the 2 models.How can I minimize this difference; which parameters should I use for the discretization in the panel Solve/controls/solution for the pressure, the density ...
I know that the convergence with the pressure based model is much more quickly, but I want to be sure that I can use these results.