[FLASH-USERS] How to properly calculate sound speed

[Tomasz Plewa]

Seyit -

The sound speed is one of the quantities defined by the equation of 
state, and so the gamma(s) in general are as well. Constant gamma is 
essentially a fairly good model applying only to relatively simple 
gases. As you already implied, the value of sound speed does not depend 
on physics processes per se but rather on the thermodynamic state of matter.

Also,

C^2 = gamma P/rho

Reviewing a few chapters in the thermodynamics textbook might be most useful, and you may want to take a look at

http://en.wikipedia.org/wiki/Speed_of_sound

Tomek
---

Seyit Hocuk wrote:
> Hi all,
>
> Within Flash, the speed of sound is calculated by "C = gamma P/rho" with 
> a constant predefined gamma. However, if you have additional physics 
> like heating, cooling, or radiative transfer effects, gamma should vary. 
> Hence, the sound speed is then calculated wrong. Gamma is in fact 
> "dlog(P)/dlog(rho)" and the sound speed is actually "dP/drho".
>
> How can one approximate, if not solve, the sound speed more carefully?
>
> One basic idea I had was to derive 'C' for a zone using a neighboring 
> zone (P2-P1/rho2-rho1) and to take the average of 'C' for an entire 
> block. That doesn't work very well.
>
> Kind regards,
> Seyit
>   
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