Add initial IMEX Runge-Kutta solvers (SSP and BHR schemes)#3341
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singhharsh1708 wants to merge 3 commits intoSciML:masterfrom
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Add initial IMEX Runge-Kutta solvers (SSP and BHR schemes)#3341singhharsh1708 wants to merge 3 commits intoSciML:masterfrom
singhharsh1708 wants to merge 3 commits intoSciML:masterfrom
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This should likely be on top of #3030 |
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The NonlienarSolve wrappers were handled: rebase and there shouldn't be an issue there. |
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| SFSDIRK7, SFSDIRK8, ESDIRK436L2SA2, ESDIRK437L2SA, ESDIRK547L2SA2, ESDIRK659L2SA, | ||
| IMEXSSP222, IMEXSSP2322, IMEXSSP3332, IMEXSSP3433, | ||
| ARS222, ARS232, ARS443, BHR553 |
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I dont' think we want to export these
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| @muladd function perform_step!( | ||
| integrator, cache::IMEXSSP222ConstantCache, repeat_step = false | ||
| ) | ||
| (; t, dt, uprev, u, p) = integrator | ||
| nlsolver = cache.nlsolver |
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It doesn't seem helpful to just write a ton of perform_step!s for these pretableau.
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| [1 0] | ||
| b̃ = [1/2, 1/2] | ||
| =# | ||
| struct IMEXSSP222Tableau{T, T2} |
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Why 222 instead of four numbers 2222 like for the others?
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This PR introduces a set of Implicit-Explicit (IMEX) Runge-Kutta solvers based on the works of Boscarino–Russo (2009) and Pareschi–Russo (2005). These methods are designed for time integration of stiff systems with a natural splitting into non-stiff (explicit) and stiff (implicit) components, i.e.,
SplitODEProblem.The implementation extends the existing SDIRK/KenCarp framework in
OrdinaryDiffEqSDIRK, since the implicit part of these methods follows an ESDIRK structure, making them compatible with the current infrastructure.Implemented Methods
From Pareschi & Russo (2005)
IMEXSSP222 — SSP2(2,2,2)
IMEXSSP2322 — SSP2(3,2,2)
IMEXSSP3332 — SSP3(3,3,2)
IMEXSSP3433 — SSP3(4,3,3)
Implementation Details
Added new algorithm types in:
algorithms.jlAdded corresponding Butcher tableaux in:
sdirk_tableaus.jlIntegrated with existing KenCarp-style stepping logic:
kencarp_kvaerno_perform_step.jlkencarp_kvaerno_caches.jlThese methods follow the IMEX formulation:
f1) handled via SDIRKf2) handled via explicit RKMotivation
Existing IMEX methods (e.g., KenCarp family) do not explicitly include:
This PR adds:
Checklist
Additional context
Based on:
This PR focuses on core solver implementation; additional variants (e.g., MARS/MARK) can be added in follow-up PRs.