Rayleigh-Benard demo using Irksome and patch smoothing #4319
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pbrubeck
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May 14, 2025
| tends to make prettier pictures for low Rayleigh numbers, but also | ||
| tends to take more Newton iterations since the coupling terms in the | ||
| Jacobian are a bit stronger. Switching to the first case would be a | ||
| simple change of bits of the boundary associated with the second and |
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Suggested change
| simple change of bits of the boundary associated with the second and | |
| simple change of the boundary subdomains associated with the second and |
* demo for steady Boussinesq problem with integral constraints * fix demo python file locations --------- Co-authored-by: David Ham <[email protected]>
…e into rckirby/brandy
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| base_msh = UnitSquareMesh(Nbase, Nbase) | ||
| mh = MeshHierarchy(base_msh, ref_levels) | ||
| msh = mh[-1] |
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Do we want a comment here as to why we're using a MeshHierarchy?
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| Like Navier-Stokes, the pressure is only defined up to a constant.:: | ||
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| nullspace = [(1, VectorSpaceBasis(constant=True))] |
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This looks wrong to me - we have 3 spaces in Z, but only 2 in the nullspace...
| butcher_tableau = RadauIIA(num_stages) | ||
| We are going to carry out time stepping via Irksome, but we need | ||
| to say how to solve the rather interesting stage-coupled system. :: |
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I feel like we should add more words about the details of the solver. There aren't a lot of demos with MMG, so explaining what we do would be worthwhile.
| "ksp_type": "fgmres", | ||
| "ksp_monitor": None, | ||
| "ksp_max_it": 200, | ||
| "ksp_atol": 1.e-12, |
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You're using Eisenstat-Walker, so why also set ksp_atol?
| "ksp_monitor": None, | ||
| "ksp_max_it": 200, | ||
| "ksp_atol": 1.e-12, | ||
| "ksp_gmres_restart": 30, |
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This seems so wrong - why bother with a restart so small?
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Description
Add a demo using Irksome for a time-dependent Rayleigh-Benard convection problem. We use a monolithic multigrid scheme with Vanka patch relaxation for the time stepping.