[JLight]

Hi
I am a UG student working on a solver for high Ma numbers using OpenFOAM for my final year project. I am relatively new to OpenFOAM.

While looking at the code of rhoCentralFoam i came across this line(s) which I am not able to figure out the menaing

if (!inviscid)
        {
            volScalarField k("k", thermo.Cp()*mu/Pr);
            solve
            (
                fvm::ddt(rho, e) - fvc::ddt(rho, e)
              - fvm::laplacian(thermo.alpha(), e)
              + fvc::laplacian(thermo.alpha(), e)
              - fvc::laplacian(k, T)
            );
            thermo.correct();
            rhoE = rho*(e + 0.5*magSqr(U));
        }

What does

fvm::ddt(rho, e) - fvc::ddt(rho, e)

really mean?

I am trying to rewrite sonicFoam energy equation using total energy and since this solver uses total energy (for inviscid - not shown above) i thought I could copy it but was not sure what is happening in the above shown code to include viscous effect.

Any help or advise will be highly appreciated!

Cheers!