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cholla-hydro / cholla

A GPU-based hydro code
https://github.com/cholla-hydro/cholla/wiki
MIT License
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Remove line introducing a bug in cosmological cooling unit system. #402

Open brantr opened 2 days ago

brantr commented 2 days ago

In chemistry_functions.cpp, relative to Bruno's cosmology version, there are changes to the unit system to allow for the CHEMISTRY_GPU modules to be used without COSMOLOGY set. The changes couch scale factor scalings or little h conversions within ifdef COSMOLOGY statements.

On line 62, there is a dens_number_conv that is scaled by a^3. In Bruno's code, this undoes a a^-3 of density_units. However, in this version of the dens_number_conv is set directly by dens_CGS, not density_units, and so the additional factor of a^3 is incorrect.

I have verified that removing line 62 addresses the bug and the results show good agreement with Bruno's version ( I have only checked with DE off to fairly high redshift, but enough to diagnose this issue).

brantr commented 2 days ago

Noting that this change is just removing a line within an ifdef COSMOLOGY, and it won't affect any other builds.