[mighelone]

I've a question about the discretization of the momentum equation in the solver rhoSimpleFoam, defined in this way:


fvm::div(phi, U)
- fvm::Sp(fvc::div(phi), U)
+ turbulence->divRhoR(U)


I don't understand the meaning of the second term fvm::Sp(fvc::div(phi),U).

The same equation in the solver rhoTurbFoam is discretized in a different way:

fvm::ddt(rho, U)
+ fvm::div(phi, U)
+ turbulence->divRhoR(U)

Someone can explain me the difference?

Thank you
Michele