[FLASH-USERS] confusion regarding abar and zbar

[John ZuHone]

Hi Jon,

I’m not an expert on the multi-temperature gamma, but I should note that the various EOS modes:

MODE_DENS_TEMP
MODE_DENS_EI
MODE_DENS_PRES

have to do with telling the EOS which quantities you have and which ones you want, so for example MODE_DENS_TEMP says “I have temperature and density and I want internal energy and pressure”, and so on. They all refer to the same EOS calculation, it just depends on which variable was most recently updated. For example, you may call the EOS with MODE_DENS_TEMP in Simulation_initBlock if you initialize density and temperature, but Hydro is going to be calling it with MODE_DENS_PRES after it updates the pressure term. 

Best,

John

> On Sep 16, 2015, at 12:10 PM, Jonathan Slavin <jslavin at cfa.harvard.edu> wrote:
> 
> Okay.  I see that now.  Sorry to be so blind.  I was confused by the table that indicates cases where the temperatures are assumed to be all equal (which is odd for a multi-temperature gamma).  So, any recommendations for a minimal multi-temperature run?  Is there any significant difference between the various 1-T modes? (For example MODE_DENS_TEMP, MODE_DENS_EI, etc.)
> 
> Jon
> 
> On Wed, Sep 16, 2015 at 11:56 AM, John ZuHone <jzuhone at space.mit.edu <mailto:jzuhone at space.mit.edu>> wrote:
> Hi Jon,
> 
> Unless I am incorrect this section refers to the “multi-temperature” Gamma EOS. Were you trying to use that or just the standard single-temperature version?
> 
> John
> 
>> On Sep 16, 2015, at 11:52 AM, Jonathan Slavin <jslavin at cfa.harvard.edu <mailto:jslavin at cfa.harvard.edu>> wrote:
>> 
>> ​Hi Dean,
>> 
>> But if you look in section 15.4.1 it states something different: 
>> "​This EOS can include contributions from radiation, partially or completely ionized nuclei, and electrons. The desired (constant) ionization level $ {\bar Z}$ of the nuclei should be specified with the eos_singleSpeciesZ runtime parameter."
>> 
>> Jon
>> 
>> On Wed, Sep 16, 2015 at 11:30 AM, Dean Townsley <Dean.M.Townsley at ua.edu <mailto:Dean.M.Townsley at ua.edu>> wrote:
>> Hi Johnathan,
>> 
>> The gamma-law EOS is just a simple ideal gas as described in section 15.2 of the user's guide:
>> http://flash.uchicago.edu/site/flashcode/user_support/flash4_ug_4p3/node22.html#SECTION06320000000000000000 <http://flash.uchicago.edu/site/flashcode/user_support/flash4_ug_4p3/node22.html#SECTION06320000000000000000>
>> 
>> As you can see from the expressions there, zbar is not used at all.  You should set abar so that these expressions give what you expect.  This is what John Zuhone and Tomek I believe are suggesting.
>> 
>> Hopefully that helps clarify,
>> Dean
>> 
>> 
>> 
>> 
>> -- 
>> ________________________________________________________
>> Jonathan D. Slavin                 Harvard-Smithsonian CfA
>> jslavin at cfa.harvard.edu <mailto:jslavin at cfa.harvard.edu>       60 Garden Street, MS 83
>> phone: (617) 496-7981 <tel:%28617%29%20496-7981>       Cambridge, MA 02138-1516
>> cell: (781) 363-0035 <tel:%28781%29%20363-0035>             USA
>> ________________________________________________________
>> 
> 
> 
> 
> 
> -- 
> ________________________________________________________
> Jonathan D. Slavin                 Harvard-Smithsonian CfA
> jslavin at cfa.harvard.edu <mailto:jslavin at cfa.harvard.edu>       60 Garden Street, MS 83
> phone: (617) 496-7981       Cambridge, MA 02138-1516
> cell: (781) 363-0035             USA
> ________________________________________________________
> 

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