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R used in thermodynamicproperties

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Old   June 13, 2008, 10:33
Default Hi I find that R is set to
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srinath
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Hi

I find that R is set to .714286J/(KgK), in most of the examples.
This does not correspond to specific gas constant of air. So is foam assuming some strange gas for the examples or am i missing something?

Univeral gas constant = 8.314J/(mol K)
Mol wt of air =29gm/mol
Therefore specific gas constant = 8.314/.029 = 287 J/(Kg K)--Also confirmed by wikipedia

Am i missing something trivial here?

Could someone please clear this, as i am trying to benchmark the solvers?

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Srinath
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Old   June 13, 2008, 11:26
Default Can you please list out the tu
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ash
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Arun Shourie
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Can you please list out the tutorials.
But in sonicFoam tutorial its given correctly only
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Old   June 13, 2008, 12:29
Default The value of R, i find in
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srinath
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The value of R, i find in

/tutorial/sonicFoam/forwardstep/constant/thermodynamicProperties is
as follows

R [0 2 -2 -1 0 0 0] 0.714286;

But i do notice that it is set to 287 in the shockTube directory.--Strange

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Old   June 16, 2008, 03:47
Default Hi If you look in the Progr
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Niels Gjoel Jacobsen
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Hi

If you look in the Programmers Guide pp 61, you will find that R is set, such that the speed of sound in air is 1 m/s.

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Niels
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Old   June 16, 2008, 06:41
Default Thanks Niels I also find in
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Thanks Niels

I also find in the Programmers guide a reference to thermal conductivity kappa.
But nowhere in the code for sonicFoam is kappa even used. It is also not mentioned in thermodynamicProperties in ver-1.4.1

Is this a minor oversight, which can be fixed trivially, by changing mu in the energy equation to kappa?

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