applications/solvers/multiphase/multiphaseInterFoam/UEqn.H

   1     surfaceScalarField muf = mixture.muf();
   2
   3     fvVectorMatrix UEqn
   4     (
   5         fvm::ddt(rho, U)
   6       + fvm::div(mixture.rhoPhi(), U)
   7       - fvm::laplacian(muf, U)
   8       - (fvc::grad(U) & fvc::grad(muf))
   9     //- fvc::div(muf*(mesh.Sf() & fvc::interpolate(fvc::grad(U)().T())))
  10     );