Use the Vortex Sheet boundary condition to model a shear layer that separates a stream from the free velocity field. Because the velocity potential is discontinuous over this boundary, use a slit boundary condition or a pair in an assembly. Vortex sheets are only applicable on interior boundaries.

where w denotes the outward normal displacement (SI unit: m) of the boundary surface, which this boundary condition adds as ae.vs1.w, using the default name for the physics interface. On pair (interior) vortex sheet conditions the up/down, that refers to the up and down side of an interior boundary, is replaced by a 1 and 2 index in the equation display. These refer to the two faces in the pair.