[FLASH-USERS] how to Implement Isothermal EOS

[Tomasz Plewa]

M.A. -

You may consult Balsara, D., 1994, ApJ, 420, 197. There is also more  
recent paper by Andrea Mignone (2007, JCP, 225, 1427). Some other  
codes do have an isothermal EoS implemented (CLAW, Athena, VH-1) as  
well as groups working on the evolution of protoplanetary disks. I  
seem to remember a paper (Blondin? Stone?) giving the exact formulae,  
but I don't have it handy.

The brute-force approach is to use a constant gamma-law (ideal) gas EoS with
gamma as close to 1.e0 as possible (e.g. 1.001). But in this case the  
solution may be numerically unstable and some provisions needs to be  
build into the Riemann solver. Using (naively) gamma=1 will almost  
certainly break the code.

The bottom line is you need to replace the existing Riemann solver  
with the isothermal version and implement an isothermal EoS.

Hope this helps.

Tomek
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M.A. Latife wrote:

> Hi all,
> I am using FLASH2.5. Is there any way to implement isothermal EOS.
> should i use heating and cooling source terms for this purpose or is
> there any other way to do this?
> kind Regards
> M.A.Latife
>
>
> -- 
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