[FLASH-USERS] Typo in unsplit_rad Hydro_computeDT

[Mark Richardson]

>
> Hey everyone,
>
>   I'm pretty sure there's a bug in the unsplit_Rad Hydro_computeDT:
> source/physics/Hydro/HydroMain/unsplit_rad/Hydro_computeDt.F90
>
> Line 241 reads:
> 241:                 if (NDIM > 2) dt_ltemp =
> max(dt_ltemp,(abs(U(VELZ_VAR,i,j,k)-uzgrid(j))+sqrt(cfz2))*delzinv)
>
> But should be:
> 241:                 if (NDIM > 2) dt_ltemp =
> max(dt_ltemp,(abs(U(VELZ_VAR,i,j,k)-uzgrid(k))+sqrt(cfz2))*delzinv)
>
>
> However, I was getting the error:
> ***********************************************************
>   Warning: The initial timestep is too large.
>     initial timestep =   1.000000000000000E-010
>     CFL timestep     =   5.215016855876254E-303
>   Resetting dtinit to dr_tstepSlowStartFactor*dtcfl.
>  ***********************************************************
> both with and without the fix above. With the fix, I dug deeper into why
> the dt was going to zero, and found that it related to guard cells. I then
> also initialized my guard cells in Simulation_initBlock and the small dt
> problem went away.
>
> Oddly, a collaborator took my SimulationMain/Code/ and ran it, and got the
> small dt error again, even with the guardCells initialized. I forgot to
> give him the above fix to Hydro_computeDT. He made that fix, and now his
> small dt problem is gone as well.
>
> I'm using the hypre unsplit solver, with radiation and mgd on. Any
> thoughts on why an intiial FillGuardCells call isn't fixing the problem?
>
> Cheers,
>   -Mark
>
> --
> Mark Richardson
> Beecroft Postdoctoral Fellow, Department of Physics
> Denys Wilkinson Building - 555F
> University of Oxford
> Mark.Richardson at physics.ox.ac.uk
> +44 1865 283020
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://flash.rochester.edu/pipermail/flash-users/attachments/20160208/dd08599a/attachment.htm>