Gridiron is an adaptive mesh refinement (AMR) library for solving time-dependent systems of conservation laws, like the Euler equations of gas dynamics. It uses structured, rectilinear grid patches in the style of Berger-Oliger AMR, where patches can be placed at different refinement levels in flexible configurations: patches may overlap one another and fine patches may cross coarse patch boundaries. This is in contrast to more constrained quad-tree / oct-tree mesh topologies used e.g. in the Flash code.
This library is a work-in-progress in early stages. Its goals are:
- Provide meshing and execution abstractions for hydrodynamics base schemes. If you have a scheme that works on logically Cartesian grid patches, this library can make that scheme suitable for AMR simulations.
- Be aggressively optimized in terms of computations (eliminating redundancy), array traversals (no multi-dimensional indexing), memory access patterns (optimal cache + heap utilization), and parallel execution strategies.
- Provide efficient strategies for hybrid parallelization based on shared memory and distributed multi-processing.
- Not to depend on other work-in-progress crates. Many HPC-oriented Rust
crates look promising, but are still in flux; this crate should not
depend on things like
ndarray,hdf5, orrsmpi. Dependencies are currently limited torayonandcrossbeam_channel.serdeis presently required in the library to support the examples, but it should be made optional. - Have fast compile times. The debug cycle for physics simulations often
requires frequent recompilation and inspection of results. Compile times
of 1-2 seconds are fine, but the code should not take 30 seconds to
compile, as can happen with lots of generics, excessive use of
async, link-time optimizations, etc. For this reason the primary data structure (patch::Patch) is not generic over an array element type; it usesf64and a runtime-specified number of fields per array element. - Provide examples of stand-alone applications which use the library.
It does not attempt to
- Be a complete application framework. Data input/output, user configurations, visualization and post-processing should be handled by separate crates or by applications written for a specific science problem.
- Provide lots of physics. The library will be written to support multi-physics applications which require things like MHD, tracer particles, radiative transfer, self-gravity, and reaction networks. However, this library does not try to implement these things. The focus is on abstractions for meshing and execution.