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VPM-B: add crushin pressure calculation.

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Add new structures holding vpm-b state.
Add function calculating current crushing pressure.
Call it from add_segment() on every ambient pressure change.
It determines what pressure acts on nuclei during the descent
and thus their size at the beggining of the deco.

Signed-off-by: Jan Darowski <jan.darowski@gmail.com>
This commit is contained in:
Jan Darowski 2015-07-03 22:10:12 +02:00
parent 94f3fc8542
commit bed3b9eea3
1 changed files with 43 additions and 0 deletions
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43
deco.c
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@ -102,6 +102,15 @@ double tolerated_by_tissue[16];
double tissue_inertgas_saturation[16];
double buehlmann_inertgas_a[16], buehlmann_inertgas_b[16];
double max_n2_crushing_pressure[16];
double max_he_crushing_pressure[16];
double crushing_onset_tension[16]; // total inert gas tension in the t* moment
double n2_regen_radius[16]; // rs
double he_regen_radius[16];
double max_ambient_pressure; // last moment we were descending
static double tissue_tolerance_calc(const struct dive *dive)
{
int ci = -1;
@ -234,6 +243,39 @@ double calc_inner_pressure(double crit_radius, double onset_tension, double curr
return onset_tension * (pow(onset_radius, 3) / pow(current_radius, 3));
}
// Calculates the crushing pressure in the given moment. Updates crushing_onset_tension and critical radius if needed
void calc_crushing_pressure(double pressure)
{
int ci;
double gradient;
double gas_tension;
double n2_crushing_pressure, he_crushing_pressure;
double n2_inner_pressure, he_inner_pressure;
for (ci = 0; ci < 16; ++ci) {
gas_tension = tissue_n2_sat[ci] + tissue_he_sat[ci] + vpmb_config.other_gases_pressure;
gradient = pressure - gas_tension;
if (gradient <= vpmb_config.gradient_of_imperm) { // permeable situation
n2_crushing_pressure = he_crushing_pressure = gradient;
crushing_onset_tension[ci] = gas_tension;
}
else { // impermeable
if (max_ambient_pressure >= pressure)
return;
n2_inner_pressure = calc_inner_pressure(vpmb_config.crit_radius_N2, crushing_onset_tension[ci], pressure);
he_inner_pressure = calc_inner_pressure(vpmb_config.crit_radius_He, crushing_onset_tension[ci], pressure);
n2_crushing_pressure = pressure - n2_inner_pressure;
he_crushing_pressure = pressure - he_inner_pressure;
}
max_n2_crushing_pressure[ci] = MAX(max_n2_crushing_pressure[ci], n2_crushing_pressure);
max_he_crushing_pressure[ci] = MAX(max_he_crushing_pressure[ci], he_crushing_pressure);
}
max_ambient_pressure = MAX(pressure, max_ambient_pressure);
}
/* 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)
{
@ -256,6 +298,7 @@ double add_segment(double pressure, const struct gasmix *gasmix, int period_in_s
tissue_n2_sat[ci] += n2_satmult * pn2_oversat * n2_f;
tissue_he_sat[ci] += he_satmult * phe_oversat * he_f;
}
calc_crushing_pressure(pressure);
return tissue_tolerance_calc(dive);
}