Draft: Magnetosonic speed in timescale used in updating the viscosity alphas

Also changed hydro parameters to what works best for me in the shock tubes, and is consistent with the value suggested for hydro. Let me know what you think.

requested review from @fastasyszyn

assigned to @matthieu

added MHD label

breaks the cosmo runs. mhd_get.... is in comoving and soundspeed_physical is in physical

Good catch, thanks

Am I right in seeing that the two changes to the parameters are reverting the values to what they are in master?

Thanks for sharing the changes. I think the cleanest way will be to create a function like get_velocity_for_viscosity() and that will either default to v_sig when no MHD and to magnetosnoic speed when running MHD.

Same as we do for the sig_vel.

Let's not do that for now. We first want to see whether everything works before starting larger engineering works.

@fastasyszyn do we want the same change in FDI?

To me this is not an entirely ad hoc modification, it comes down to how you choose to time integrate your viscosity alphas (eq. 24 in the SPHENIX paper). If we want to do viscosity the same way across all schemes, this should be applicable to all MHD flavours.

I'll wait until we have worked out the scale-factors before merging as I don't want to break the cosmo runs.

Todo:

• Show what the cosmology terms should be.
• (Matthieu:) Once terms are known, sort out the function to work with all hydro schemes.

Any updates on the above?

idem, what happened with this? My guess is that anything that works better in the Hydro will be good for all schemes.... so If is tested and OK, please merge

Any updates on the above?

marked this merge request as draft

What about this branch? Since we are talking about time integration... Do we care?

Closing as no activity.

closed