[FLASH-USERS] hydrostatic models in flash

[Philip Chang]

Hi Dongwook,

Thanks for the quick reply.

As Suoqing alluded to, I am using the using the unsplit solvers because 
I would like to include rotation in my models eventually. I have given 
some thought to using the split PPM solver and including a centrifugal 
term.  But I have not done so because I got interested in my problem 
when FLASH 4 came out and realized that a 2.5 d solver was already in there.

As for your questions,
> You can still check your simulations runs as you expected by using the
> split PPM solver for the testing purpose if needed. But in order to
> understand your concern correctly, I would like to understand more on your
> statement "2.5d (and hence, the unsplit solvers)". Can you explain this to
> me more?

yes, my desire is to include rotation in 2.5 d.  But right now my 
testing models are not rotating so I should go ahead and test these 
models with the split solver to see if this occurs in it as well.

>
>> However, as I am reading FLASH, it seems that this
>> cancellation may be built in.  In particular, for the unsplit solvers,
> Just to understand correctly: You say "unsplit solvers". And I am guessing
> you are using the unsplit "hydro" solver, rather than the MHD one,
> correct?

I am using the hydro solver, not the MHD one.
>> it seem that gravity is used to calculate the various fluxes.  But I am
>> not sure.  Is there some combination of use_gravHalfUpdate,
>> use_gravConsv, or use_GravPotUpdate in the unsplit solver that would
>> have the same effect as ppm_modifystates = .true. in the split PPM solver?
> Such implementation of ppm_modifistates=.true. in the split PPM solver has
> not been implemented in the unsplit (hydro & MHD) solvers, but it can
> certainly be done easily.
I agree with this.  having looked at the modifications that 
ppm_modifystates, its look simplier to implement this in the unsplit 
solvers than to include centrifugal terms in the split PPM solver 
(though I could be wrong).
>
> As for those gravity switches, the choices you want to use are the
> following (although they are not giving you the same effect as
> ppm_modifystates=.true.):
>
> use_gravHalfUpdate = .true.
> use_gravConsv = .false.
> use_gravPotUpdate = .false.
>
> If you wish you can send me your log file and flash.par, I will have a
> look at them.
I'll send this to you in a separate e-mail as to not flood flash-users 
with attachments.

Cheers,
Phil