[FLASH-USERS] Trying to use viscosity

[Reyes, Adam]

Hi Max,

Yes you’re right those should be commas. 

I would recommend against using those combinations of solvers. The unspilt hydro solver, which has its' own implementation of flux-based diffusion solvers is in general better for multidimensional flows. It is also better maintained than the split solvers. You could have in you Config this instead:

REQUIRES Driver
REQUIRES physics/Hydro/HydroMain/unsplit
REQUIRES Multispecies/MultispeciesMain
REQUIRES physics/Eos/EosMain/Multigamma

 this <https://doi.org/10.1088/0004-637x/715/2/1221> paper on the CASTRO code has some pretty striking figures showing the advantages of using an unspilt hydro solver.

You shouldn’t need to add those parameters to your own simulation Config. They exist elsewhere in the source code and make them available to be set from you flash.par at runtime.

Thanks for reporting the bug!


*********************************************
Adam Reyes


Code Group Leader, Flash Center for Computational Science  
Research Scientist, Dept. of Physics and Astronomy
University of Rochester
River Campus: Bausch and Lomb Hall, 369  
500 Wilson Blvd. PO Box 270171, Rochester, NY 14627
Email adam.reyes at rochester.edu
Web https://flash.rochester.edu
 (he / him / his)


*********************************************



> On Oct 7, 2023, at 8:21 AM, Maximus Allfree <mall7710 at uni.sydney.edu.au> wrote:
> 
> Hey FLASH Users,
> 
> 
> I am having some problems with diffusion and viscosity. I am trying to run RMI simulations and have required these in the config file:
> 
> REQUIRES Driver
> REQUIRES physics/Hydro/HydroMain/split/PPM
> REQUIRES Multispecies/MultispeciesMain
> REQUIRES physics/Eos/EosMain/Multigamma
> REQUIRES physics/Diffuse/DiffuseFluxBased
> 
> In the flash user documentation it mentioned that HYDRO PPM was needed for diffusive effects, so I am using that. Before I was just using physics/Hydro. I also am using DiffuseFluxBased so I can use heat conduction and viscosity. 
> 
> I have the following parameters in the config file to set the required runtime variables. I have also set these in the flash.par file, but they don't seem to do anything? They aren't overriding the config file default values. Not sure if I have done something wrong here, or if they're not meant to be used in the flash.par file:
> 
> # Diffusive parameters:
> D useDiffuse flags whether the Diffuse unit is being used at all
> PARAMETER   useDiffuse          BOOLEAN     true
> 
> D useDiffuseTherm flags whether Diffuse_therm should contribute to fluxes
> PARAMETER   useDiffuseTherm     BOOLEAN     true
> 
> D useDiffuseVisc flags whether Diffuse_visc should contribute to fluxes
> PARAMETER   useDiffuseVisc      BOOLEAN     true
> D useViscosity flags whether the viscosity material property is being used
> PARAMETER   useViscosity        BOOLEAN     true
> 
> D diff_visc_mu constant dynamic viscosity 
> PARAMETER   diff_visc_mu        REAL        0.1         [ to ]
> 
> D diff_visc_nu constant kinematic viscosity 
> PARAMETER   diff_visc_nu        REAL        0.1         [ to ]
> 
> D visc_whichCoefficientIsConst which is constant: (1 for dynamic, 2 for kinematic)
> PARAMETER   visc_whichCoefficientIsConst    INTEGER     1   [1 to 2]
> 
> 
> Anyway, when I try to make the code, I am getting this error:
> 
> /opt/homebrew/Cellar/mpich/4.1.2/bin/mpif90 -ggdb -c -O2 -fdefault-real-8 -fdefault-double-8 -Wuninitialized -fallow-argument-mismatch -ffree-line-length-none  -DMAXBLOCKS=1 -DNXB=45 -DNYB=32 -DNZB=1 -DN_DIM=2 Diffuse_visc.F90
> Diffuse_visc.F90:225:59:
> 
>   225 |               call Viscosity(U(:,i,j,k),viscDynamic(i,j,k).viscUnusedHere(i,j,k), component=1)
>       |                                                           1
> Error: Syntax error in argument list at (1)
> Diffuse_visc.F90:327:52:
> 
>   327 |               call Viscosity(U(:,i,j,k),viscDynamic(i,j,k).viscUnusedHere(i,j,k), component=1)
>       |                                                    1
> Error: Syntax error in argument list at (1)
> Diffuse_visc.F90:411:52:
> 
>   411 |               call Viscosity(U(:,i,j,k),viscDynamic(i,j,k).viscUnusedHere(i,j,k), component=1)
>       |                                                    1
> Error: Syntax error in argument list at (1)
> make: *** [Diffuse_visc.o] Error 1
> 
> I looked into the Diffuse_visc.F90 file, and I was wondering whether the full stops are meant to be commas? It feels unlikely that this would be a FLASH error and far more likely I have done something wrong with implementing diffusion / viscosity as I am new to FLASH but I figured I would ask if anyone else has had problems with this.
> 
> Cheers for reading. Any advice would be greatly appreciated.
> 
> 
> Kind regards,
> Max
> 
> 
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> 
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