The General Interior Flux node, found under the
More submenu, adds the most general interior boundary condition for the convected wave equation, as it is formulated (in the conservative form) for the discontinuous Galerkin method (dG). The condition defines the normal flux
g on an interior boundary by
here Γ* represents the total numerical flux. This means that if this condition is added on an interior boundary it overrides the existing Lax–Friedrichs numerical flux. So care should be taken when specifying this condition as it needs to include the necessary numerical flux contribution to ensure stability of the method.
On an interior boundary you can use the up() and
down() operators to access values from both sides of the boundary. If a dependent variable is used in this expression (without
up() or
down() operators) an implicit
mean() operation is invoked taking the average of the up and down side values. Use the mesh normals (
nxmesh,
nymesh, and
nzmesh; or
nrmesh,
nphimesh, and
nzmesh) in the expression you define.
