Binary Neutron Star Mergers on a Moving Mesh

Arbitrary Lagrangian-Eulerian (ALE) schemes capture the best features of both grid-based and smooth particle hydrodynamics (SPH) methods, drawing an unstructured moving mesh (MM) around the particles' positions that adapts during the simulation. ALE/MM schemes resolve shocks as well as grid-based schemes, and errors associated with the numerical grid are minimized since the mesh conforms to the fluid's geometry.

This talk discusses a new combined code, BlackHoles@Home (BH@H)/MANGA, for modeling binary neutron star (BNS) mergers. MANGA solves the general relativistic hydrodynamics equations using an ALE/MM scheme with Voronoi tessellation, while BH@H solves the general relativistic field equations on super-efficient, multi-patch, multi-coordinate structured grids that are specifically tuned for compact binary mergers. By combining the two, we leverage optimal grids for both the spacetime and hydrodynamics fields, significantly reducing the number of required sampling points by up to two orders of magnitude.