[edmund32]

Hi,
I was just looking at the momentum equation for an incompressible MHD flow online (https://www.openfoam.com/documentati...utorialse4.php) and saw that is was slightly different in mhdfoam.C:
The equation in that link is:

 fvm::ddt(U) + fvm::div(U, U)
 - fvc::div(B, 2.0*DBU*B)
 - fvm::div(nu, U)
 + fvc::grad(DBU*magSqr(B))

 == -fvc::grad(p));

While the one in mhdFoam is

 fvm::ddt(U) + fvm::div(phi, U)
 - fvc::div(phiB, 2.0*DBU*B)
 - fvm::laplacian(nu, U)
 + fvc::grad(DBU*magSqr(B))

 == -fvc::grad(p));

I know I'm just being stupid, but why is phi and phiB used instead of U and B? And why is the vicosity term a laplacian operator rather than a divergence?

Thanks!
Edmund