Weakly Compressible Flow
The same equations as for Compressible Flow are applied for weakly compressible flow. The only difference is that the density is evaluated at the reference pressure. The density may be a function of other quantities, in particular it may be temperature dependent.
The weakly compressible flow equations are valid for incompressible as well as compressible flow with density variations independent of the pressure.
Provided that the densities dependency pressure is specified through model inputs, the density is automatically evaluated at the reference pressure level.