Vectorization of High-Order DG in Ateles for the NEC SX-ACE

In this chapter, we investigate the possibilities of deploying a high-order, modal, discontinuous Galerkin scheme on the SX-ACE. Our implementation Ateles is written in modern Fortran and requires the new sxf03 compiler from NEC. It is based on an unstructured mesh representation that necessitates indirect addressing, but allows for a large flexibility in the representation of geometries. However, the degrees of freedom within the elements are stored in a rigid, structured array. For sufficiently high-order approximations these data structures within the elements can be exploited for vectorization.