Characteristic Boundary Conditions

Characteristic boundary conditions are currently available only in the z-direction. The Cartesian mesh solver path (i_grid=1) has characteristic BCs implemented at both the lower and upper boundaries. These are activated by setting iubc_z0=1 and/or iubc_z1=1. The solver paths for the other grid types currently only have characteristic conditions implemented at the upper boundary.

A reference for the characteristic conditions is https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19790020779.pdf.