[huyidao]

Hello,everyone.I just start to read the code of simpleFoam,and I have some problems with the continuity errors.Here is the code:

33 volScalarField contErr(fvc::ddt(alphac) + fvc::div(alphacf*phic));
35 scalar sumLocalContErr = runTime.deltaTValue()*
36 mag(contErr)().weightedAverage(mesh.V()).value();
37
38 scalar globalContErr = runTime.deltaTValue()*
39 contErr.weightedAverage(mesh.V()).value();
40 cumulativeContErr += globalContErr;

I read this thread ,but I still have some questions:
(1) phi=U&mesh.Sf()
div(phi) = div(U) = div(U&mesh.Sf())
is this still right? According to the code,I think div(phic)=div(U),which one is
right?
(2) what does the alphac and alphacf mean?
(3) does mag(scalar) mean the absolute value of the scalar?
Thanks.