Default CFL to 0.999 instead of 0.7 #2940
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MaxThevenet
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changes input scripts / defaults
ax3l
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Mar 8, 2022
Source/WarpX.H
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| @@ -1281,7 +1281,7 @@ private: | |||
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| int regrid_int = -1; | |||
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| amrex::Real cfl = amrex::Real(0.7); | |||
| amrex::Real cfl = amrex::Real(0.99); | |||
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Just in case: I usually use 0.999 for all my sims, which is a bit closer not leaving 1% on the table for time steps and still far from machine precision to be rounded to 1.
Suggested change
| amrex::Real cfl = amrex::Real(0.99); | |
| amrex::Real cfl = amrex::Real(0.999); |
I base this on Figure 2.11 in https://doi.org/10.5281/zenodo.3266820 & Figure 2.10 in https://doi.org/10.5281/zenodo.15924, where I still find the difference is signficant for the third digit.
3 tasks
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Do we want to merge this into #2941, so we only need to reset the checksums once? |
Co-authored-by: Axel Huebl <[email protected]>
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We could reset the benchmark, or explicitly set the CFL to 0.7 in the few tests that were failing, to avoid breaking them. I implemented the latter, but I don't mind either way. |
ax3l
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This PR proposes to:
warpx.cflparameter is not labeled as optional)0.7currently to0.999)My impression is that the second point would make a better default, but that changes the default which could affect users, so I am opening this PR to launch the discussion.