basic question on phiv in rhoSonicFoam
 

Hi,

I'm just looking at the rhoSonicFoam file. The phiv is defined as follows:

surfaceScalarField phiv
(
IOobject
(
"phiv",
runTime.timeName(),
mesh,
IOobject::NO_READ,
IOobject::NO_WRITE
),
fvc::interpolate(rhoU)/fvc::interpolate(rho) & mesh.Sf()
);

But why not use "fvc::interpolate(U) & mesh.Sf()" instead of the last line there? I've tried it and it does not make much difference, but some values differ then.
So I think there is a reason for taking the upper version, but I don't know which, since the latter should calculate faster. Is the first one more accurate?