Combining Cauchy and characteristic codes. V. Cauchy-characteristic matching for a spherical spacetime containing a perfect fluid

This paper is part of a long term program to develop CCM (combined Cauchy and characteristic) codes as investigative tools in numerical relativity. The approach has two distinct features: (i) it dispenses with an outer boundary condition and replaces this with matching conditions at an interface between the Cauchy and characteristic regions, and (ii) by employing a compactified coordinate, it proves possible to generate global solutions. In this paper it is shown that CCM can be used effectively to model a spherically symmetric perfect fluid. A particular advantage of CCM in avoiding arbitrary mass inflow-outflow boundary conditions is pointed out. Results are presented which include fluid distributions which form black holes and those which give rise to mass outflow.