NRPyElliptic: A Fast Hyperbolic Relaxation Solver for Numerical Relativity

NRPyElliptic is a new elliptic solver for numerical relativity (NR) built on the NRPy+ infrastructure. As its first application, it sets up conformally flat, binary puncture initial data on prolate-spheroidal-like grids, similar to the widely used TwoPunctures code. However, unlike TwoPunctures NRPyElliptic employs a hyperbolic relaxation scheme, whereby an elliptic equation is transformed into a hyperbolic equation. Our hyperbolic relaxation scheme has new performance enhancements that speed up the solver by orders of magnitude over the original approach, making it fast enough to generate compact binary initial data for NR. We report on current efforts to make NRPyElliptic compatible with the BlackHoles@Home multi-patch grid structure and extend the solver to generate other types of initial data. Our code has been developed as an Einstein Toolkit thorn and as a stand-alone code, both of which are documented in pedagogical Jupyter notebooks.