ECP 6: Establish and improve strong scaling of linear solves on high aspect ratio meshes

[spdomin]

Activities:

1. Evaluate current solver technologies for high aspect ratio meshes.
2. Develop improved coarsening and preconditioning techniques.
3. Evaluate possible algorithmic discretization approach improvements.
4. Explore approximate LHS contribution’s effect on linear and nonlinear solver convergence.

[spdomin]

Previous comments captured under spdomin/Nalu:

@spdomin I'd like to start by identifying a set of canonical tests with high aspect ratios and benchmarking their performance. Ideally, the tests wouldn't be too large, so that some analysis might be possible.

@jhux2 Sounds great. The heatedWaterChannel is one that you used before. I can find more next week.

[spdomin]

@jhux2 I added a new test for you under /home/spdomin/channelFlow.tar

This is a simple LES channel flow with high AR (around 50). The standard milestone.xml usage results in around 65 iterations. Dropping sensitivities helps. Hope this helps. The case can be run on 8 core without any issue (around a million elements). I think that will be a good case, however, let me know if you need something smaller (harder to find a good case though)..

[spdomin]

Transition to Jira.