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2016-03-03gas model: simplify and improve our Z factor calculationsGravatar Linus Torvalds
Lubomir found better compressibility data for the pure gases that we need for scuba, making the air table superfluous: we get good values from just regular linear mixing of the Oxygen, Nitrogen and Helium calculations. Also, rather than using a quintic polynomial, a cubic one does sufficiently well, making for smaller code and fewer coefficients. And judging by the reactions from people on G+ (as well as just looking at how good the fit is with the air data), this is all the right way to do this, and this thus removes the Redlich-Kwong equation. All-credit-goes-to: Lubomir I. Ivanov <neolit123@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
2016-03-02gas model: add polynomials for Z factors of oxygen/nitrogen/heliumGravatar Linus Torvalds
.. and use a linear mix of them for arbitrary gas mixes. For the special case of air, we continue to use the air-specific polynomial. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
2016-03-02gas model: replace Redlich-Kwong with least-square quinticGravatar Linus Torvalds
This goes back to just doing air compressibility, but using the least-squares quintic polynomial equation that Lubomir generated based on the Wikipedia table for air at 300K in the 1-500 bar range. We might be able to do similar things for mixed gases.. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
2016-03-02gas model: split up gas compressibility into a file of its ownGravatar Linus Torvalds
The gas compressibility is such a specialized thing that I really prefer having it separate. This keeps Robert's Redlich-Kwong equation as-is, but let's experiment with other models soon... Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Dirk Hohndel <dirk@hohndel.org>