diff --git a/acc/mhd_solver/stencil_kernel.ac b/acc/mhd_solver/stencil_kernel.ac index 0f37ea5..3aec600 100644 --- a/acc/mhd_solver/stencil_kernel.ac +++ b/acc/mhd_solver/stencil_kernel.ac @@ -449,11 +449,14 @@ induction(in VectorField uu, in VectorField aa) // yes this actually works. See pg.28 in arXiv:astro-ph/0109497) // u cross B - AC_eta * AC_mu0 * (AC_mu0^-1 * [- laplace A + grad div A ]) const Vector B = curl(aa); - const Vector grad_div = gradient_of_divergence(aa); + //MV: Due to gauge freedom we can reduce the gradient of scalar (divergence) from the equation + //const Vector grad_div = gradient_of_divergence(aa); const Vector lap = laplace_vec(aa); // Note, AC_mu0 is cancelled out - const Vector ind = cross(value(uu), B) - AC_eta * (grad_div - lap); + //MV: Due to gauge freedom we can reduce the gradient of scalar (divergence) from the equation + //const Vector ind = cross(value(uu), B) - AC_eta * (grad_div - lap); + const Vector ind = cross(value(uu), B) + AC_eta * lap; return ind; }