AMReX-Astro / AMReX-Astro/Castro

`simple_convection` problem encounters negative density with SDC 4th order

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Dominant language
C++
Stars
340
Forks
105
Avg merge
3d 8h
Merged PRs (30d)
8

Description

When running simple_convection built as:

make USE_TRUE_SDC=TRUE
./Castro2d.gnu.MPI.TRUESDC.ex inputs_2d castro.time_integration_method=2 castro.sdc_order=4

we get negative densities at the top of the atmosphere. This is likely because of the average -> cell-center conversion. We should adopt the strategy from pyro where we mask a zone and drop to second-order if we violate rho < 0 or e < 0 (see
https://github.com/python-hydro/pyro2/pull/309)

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Research direction

Reproduce the issue with inputs_2d using the shown TRUE_SDC build and SDC order 4 command. Read the average-to-cell-center conversion and compare the proposed masking and second-order fallback strategy with python-hydro/pyro2 pull request 309. Done means simple_convection no longer produces negative density or internal energy at the top of the atmosphere.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
hpc
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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