http://arxiv.org/abs/2204.01757
A wide array of astrophysical systems can only be accurately modelled when the behaviour of their baryonic gas components is well understood. The residual distribution (RD) family of partial differential equation (PDE) solvers can be used to solve the fluid equations, which govern this gas. We present a new implementation of the RD method to do just this. The solver efficiently and accurately calculates the evolution of the fluid, to second order accuracy in both time and space, across an unstructured Delaunay triangulation, built from an arbitrary distribution of vertices, in either 2D and 3D. We implement a novel new variable time stepping routine, which applies a drifting mechanism to greatly improve the computational efficiency of the method. We conduct extensive testing of the new implementation, demonstrating its innate ability to resolve complex fluid structures, even at very low resolution. Our implementation can resolve complex fluid structures with as few as 3-5 resolution elements, demonstrated by Kelvin-Helmholtz and Sedov blast tests. It includes three residual calculation modes, the LDA, N and blended schemes, each designed for different scenarios. These range from smooth flows (LDA), to extreme shocks (N), and scenarios where either may be encountered (blended). We compare our RD solver results to state-of-the-art solvers used in other astrophysical codes, demonstrating the competitiveness of the new approach, particularly at low resolution. This is of particular interest in large scale astrophysical simulations, where important structures, such as star forming gas clouds, are often resolved by small numbers of fluid elements.
B. Morton, S. Khochfar and Z. Wu
Wed, 6 Apr 22
30/68
Comments: 20 pages, 20 figures