Add Body Forces

[wilfonba]

Description

This PR adds oscillating and constant body forces in all three coordinate directions for the study of liquid gas interface breakup.

Fixes #275

Type of change

Please delete options that are not relevant.

• [x] New feature (non-breaking change which adds functionality)

Scope

• [x] This PR comprises a set of related changes with a common goal

How Has This Been Tested?

Case 1: 2D Rayleigh Taylor Instability This test shows the Rayleigh Taylor instability in 2 dimensions. This simulation was run using 2 Nvidia V100s on PACE Phoenix. The case file is available in examples/2D_rayleigh_taylor/case.py. Validation is accomplished through comparison to linear theory.

https://github.com/MFlowCode/MFC/assets/48168887/114b9725-b7eb-4f1d-8a4d-1527b37d62fc

Case 2: 3D Rayleigh Taylor Instability This test shows the Rayleigh Taylor instability in 3 dimensions. This simulation was run using 24 Nvidia V100s on PACE Phoenix. The case file is available in examples/3D_rayleigh_taylor/case.py. Validation is accomplished through comparison to linear theory.

https://github.com/MFlowCode/MFC/assets/48168887/cbc98c6a-181d-46df-9402-308f9e2cd295

Checklist

• [x] I have added comments for the new code
• [x] I added Doxygen docstrings to the new code
• [x] I have made corresponding changes to the documentation (docs/)
• [x] I have added regression tests to the test suite so that people can verify in the future that the feature is behaving as expected
• [x] I have added example cases in examples/ that demonstrate my new feature performing as expected. They run to completion and demonstrate "interesting physics"
• [x] I ran ./mfc.sh format before committing my code
• [x] New and existing tests pass locally with my changes, including with GPU capability enabled (both NVIDIA hardware with NVHPC compilers and AMD hardware with CRAY compilers) and disabled
• [x] This PR does not introduce any repeated code (it follows the DRY principle)
• [x] I cannot think of a way to condense this code and reduce any introduced additional line count

If your code changes any code source files (anything in src/simulation)

To make sure the code is performing as expected on GPU devices, I have:

• [x] Checked that the code compiles using NVHPC compilers
• [x] Checked that the code compiles using CRAY compilers
• [x] Ran the code on either V100, A100, or H100 GPUs and ensured the new feature performed as expected (the GPU results match the CPU results)
• [x] Ran the code on MI200+ GPUs and ensure the new features performed as expected (the GPU results match the CPU results)
• [x] Enclosed the new feature via nvtx ranges so that they can be identified in profiles
• [x] Ran a Nsight Systems profile using ./mfc.sh run XXXX --gpu -t simulation --nsys, and have attached the output file (.nsys-rep) and plain text results to this PR nsys.txt
• [x] Ran an Omniperf profile using ./mfc.sh run XXXX --gpu -t simulation --omniperf, and have attached the output file and plain text results to this PR. rocm.txt
• [x] Ran my code using various numbers of different GPUs (1, 2, and 8, for example) in parallel and made sure that the results scale similarly to what happens if you run without the new code/feature