AN ALTERNATIVE TO UNSTRUCTURED GRIDS FOR COMPUTING GAS-DYNAMIC FLOWS AROUND ARBITRARILY COMPLEX 2-DIMENSIONAL BODIES

Within the shock-capturing community, the need to simulate flows around geometrically complex bodies has resulted in an inexorable shift away from schemes which employ body-fitted grids to schemes which employ unstructured grids. Although unstructured grids are undeniably effective, in view of the increasing reliance placed on computational results, such a wholesale shift in mentality should give cause for concern. The concept of using several computer codes to cross-check numerical results becomes ill-founded if all codes follow the same methodology. In this paper we describe an alternative approach for dealing with arbitrarily complex two-dimensional geometries, the so-called Cartesian boundary method. Conceptually, the Cartesian boundary method is quite simple. Solid bodies blank out areas of a background, Cartesian mesh, and the resultant cut cells are singled out for special attention. However, there are several obstacles that must be overcome in order to achieve a practical scheme. We present a general strategy that overcomes these obstacles, together with details of our successful conversion of an adaptive mesh algorithm from a body-fitted code to a Cartesian boundary code.