mifr/subsurface
1
0
Fork 0
mirror of https://github.com/subsurface/subsurface.git synced 2025-02-01 01:43:23 +00:00
Code Issues Projects Releases Packages Wiki Activity

VPM-B: add calculating nucleons inner pressure.

Browse source 
This function calculates the pressure inside the nucleon
during the impermeable phase.
In the original code, Newton's method is used, for simplicity, we
use binary search for finding cubic equations root.

Signed-off-by: Jan Darowski <jan.darowski@gmail.com>
This commit is contained in:
Jan Darowski 2015-07-03 21:50:39 +02:00
parent 1147100930
commit 94f3fc8542
1 changed files with 37 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

37
deco.c
View file

@ -197,6 +197,43 @@ double he_factor(int period_in_seconds, int ci)
return cache[ci].last_factor;
}
// Calculates the nucleons inner pressure during the impermeable period
double calc_inner_pressure(double crit_radius, double onset_tension, double current_ambient_pressure)
{
double onset_radius;
double current_radius;
double A, B, C, low_bound, high_bound, root;
double valH, valL;
int ci;
const int max_iters = 10;
// const, depends only on config.
onset_radius = 1.0 / (vpmb_config.gradient_of_imperm / (2.0 * (vpmb_config.skin_compression_gammaC - vpmb_config.surface_tension_gamma)) + 1.0 / crit_radius);
// A*r^3 + B*r^2 + C = 0
A = current_ambient_pressure - vpmb_config.gradient_of_imperm + (2.0 * (vpmb_config.skin_compression_gammaC - vpmb_config.surface_tension_gamma)) / onset_radius;
B = 2.0 * (vpmb_config.skin_compression_gammaC - vpmb_config.surface_tension_gamma);
C = onset_tension * pow(onset_radius, 3);
// According to the algorithm's authors...
low_bound = B / A;
high_bound = onset_radius;
valH = high_bound * high_bound * (A * high_bound - B) - C;
valL = low_bound * low_bound * (A * low_bound - B) - C;
// Binary search for equations root.
for (ci = 0; ci < max_iters; ++ci) {
current_radius = (high_bound + low_bound) *0.5;
root = (current_radius * current_radius * (A * current_radius - B)) - C;
if (root >= 0.0)
high_bound = current_radius;
else
low_bound = current_radius;
}
return onset_tension * (pow(onset_radius, 3) / pow(current_radius, 3));
}
/* add period_in_seconds at the given pressure and gas to the deco calculation */
double add_segment(double pressure, const struct gasmix *gasmix, int period_in_seconds, int ccpo2, const struct dive *dive, int sac)
{