The Interior Flux Split boundary condition can be used on interior boundaries only. Compared to the Interior Flux node, the Interior Flux Split node makes it possible to specify the numerical flux separately on the upside and downside of the interior boundary. With this node, the boundary condition is enforced according to:
where gd and
gu can be specified as the flux on the downside and the upside, respectively. Here,
dn is the outward normal from the downside and
un is the outward normal from the upside.
