Flute acoustics: measurement, modelling and design - School of ...

202 APPENDIX B. PROGRAM LISTINGS
1.0,
t,
pow(t, 2),
x_w,
t * x_w,
pow(t, 2) * x_w,
p,
t * p,
pow(t,2) * p,
x_c,
t * x_c,
pow(t, 2) * x_c,
pow(x_w, 2),
pow(p, 2),
pow(x_c, 2),
x_w * p * x_c
};
for (i = 0; i < 16; i++)
c += a[i] * coeff[i];
return c;
}
double densityAirIdeal(double t, double p, double h, double x_c) {
/* temperature in Kelvin */
double T = 273.15 + t;
/* gas constant for dry air in J/kg.K */
double R_a = 287.05;
/* gas constant for water vapour in J/kg.K */
double R_w = 461.5;
/* gas constant for carbon dioxide in J/kg.K */
double R_c = 189;
/* partial pressures of dry air, water vapour and CO2 */
double p_a, p_w, p_c;
p_w = h*saturationVapourPressureWater(T);
p_c = x_c * p;
p_a = p - p_w - p_c;
}
return p_a / (R_a * T) + p_w / (R_w * T) + p_c / (R_c * T);
double densityAirGiacomo(double t, double p, double h, double x_c) {
double T = 273.15 + t;
double R = 8.314472;
double M_w = 18.015e-3;
double M_a, f, p_sv, x_w, Z;
M_a = (28.9635 + 12.011 * (x_c - 0.0004)) * 1e-3;
/* Calculate mole fraction of water vapour using equation in Cramer
Appendix (p. 2515) */
f = 1.00062 + 3.14e-8*p + 5.6e-7*pow(t,2);
p_sv = saturationVapourPressureWater(T);
x_w = h*f*p_sv/p;
Z = compressibilityAir(t, p, x_w);
return p * M_a * (1 - x_w * (1 - M_w / M_a)) / (Z * R * T);
}
double compressibilityAir(double t, double p, double x_w) {