[PATCH 03/10] VPM-B: Use correct gamma values

Rick Walsh rickmwalsh at gmail.com
Sat Aug 29 05:38:30 PDT 2015


In other implementations of VPM-B, surface_tension_gamma and
skin_compression_gammaC are taken as 0.0179 N/msw and 0.257 N/msw respectively.
We do pressure calculations in bar, not msw, so our gamma values need to reflect
that.  Previously we had used 0.179 and 2.57, which are close but not quite
correct (10 msw == 1.01325 bar).

Signed-off-by: Rick Walsh <rickmwalsh at gmail.com>
---
 deco.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/deco.c b/deco.c
index 7a9f33e..a9dbf4c 100644
--- a/deco.c
+++ b/deco.c
@@ -52,8 +52,8 @@ struct vpmb_config {
 	double crit_radius_He;            //! Critical radius of He nucleon (microns).
 	double crit_volume_lambda;        //! Constant corresponding to critical gas volume (bar * min).
 	double gradient_of_imperm;        //! Gradient after which bubbles become impermeable (bar).
-	double surface_tension_gamma;     //! Nucleons surface tension constant (N / 10m).
-	double skin_compression_gammaC;   //! Skin compression gammaC (N / 10m).
+	double surface_tension_gamma;     //! Nucleons surface tension constant (N / bar = m2).
+	double skin_compression_gammaC;   //! Skin compression gammaC (N / bar = m2).
 	double regeneration_time;         //! Time needed for the bubble to regenerate to the start radius (min).
 	double other_gases_pressure;      //! Always present pressure of other gasses in tissues (bar).
 };
@@ -63,8 +63,8 @@ struct vpmb_config vpmb_config = {
 	.crit_radius_He = 0.45,
 	.crit_volume_lambda = 199.58,
 	.gradient_of_imperm = 8.2,
-	.surface_tension_gamma = 0.179,
-	.skin_compression_gammaC = 2.57,
+	.surface_tension_gamma = 0.18137175,	// = 0.0179 N/msw
+	.skin_compression_gammaC = 2.6040525,	// = 0.257 N/msw
 	.regeneration_time = 20160.0,
 	.other_gases_pressure = 0.1359888
 };
-- 
2.4.3



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