09:10 AM - 09:50 AM (40 min)
Wolfgang Tichy (Florida Atlantic University)
Abstract: We give an introduction to the SGRID code that is intended to solve any partial differential equation (PDE). The principal spatial discretization used in SGRID is a pseudo-spectral method. Together with a Runge-Kutta time integrator it can be used to solve hyperbolic PDEs. In the past we have used it to evolve the BSSNOK equations for single excised black holes. However, we now mostly use it to solve elliptic PDEs. Currently SGRID’s main application is to solve the conformal thin sandwich equations to construct initial data for binary neutron stars with arbitrary masses and spins. To deal with complicated spatial geometries such as excision regions, or spheroidal regions comprising the interior of star, the spatial domain is split into several patches that are each covered with their own coordinate system. In its own coordinates each patch ranges over a region that has the shape of a box, but via a coordinate transformation to global Cartesian coordinates each patch can be given a different shape. SGRID is OpenMP parallelized, by distributing loops over grid points or over patches among a desired number of threads. In this talk we explain the purpose and structure of SGRID. We also discuss how one uses it and how one can extend it.