New paper on mixed-element operators in Computer Physics Communications

Spectral element codes are usually tuned for hexahedral elements, but a mesh of a real geometry also contains prisms, pyramids and tetrahedra. In a new paper in Computer Physics Communications, J. Y. Xing, B. Xia, D. Renner, C. D. Cantwell, D. Moxey, R. M. Kirby and S. J. Sherwin work out how operators such as the mass and Helmholtz matrices should be implemented for each of those shapes, on GPUs and on vectorised CPUs. The best strategy depends on the element shape, the polynomial order and the machine, and on a GPU the Helmholtz operator on tetrahedra ends up at most 2.5 times slower than on hexahedra, despite needing six times as many floating-point operations.