This thesis describes the development and implementation of subsonic boundary conditions in compressible flow codes. A one-dimensional compressible flow solver was written to be used as a testing ground for the subsonic boundary conditions. This flow solver is a finite-volume formulation that computes the transient solution to quasi-one-dimensional flows with moderate area change.
A number of subsonic boundary conditions were researched in the literature and then implemented into both one-dimensional and two-dimensional flow solvers. The code MB_CNS was used for the two-dimensional implementations. The boundary conditions tested and successfully implemented include; a resevoir inflow boundary condition, a non-reflecting inflow boundary condition, a static pressure outflow boundary condition and a non-reflecting outflow boundary condition.
The reservoir inflow boundary condition was extended to the two-dimensional code, tested and then applied. This boundary condition was used to model the injection of gas at the surface of a blunt body flow field. In particular, the MUSES-C capsule experiments with gas injection, performed in the X-2 expansion tube, were modelled. The other application of the reservoir boundary condition was to simulate an opposing jet into oncoming supersonic flow.