57 static Evaluation
gasDiffCoeff(Evaluation temperature, Evaluation pressure)
62 temperature = max(temperature, 1e-9);
63 temperature = min(temperature, 500.0);
64 pressure = max(pressure, 0.0);
65 pressure = min(pressure, 1e8);
69 const double Tb_x = 412.0;
70 const double sigma_a = 3.711;
71 const double T_scal_a = 78.6;
72 const double V_B_x = 140.4;
73 const double sigma_x = 1.18*std::pow(V_B_x, 0.333);
74 const double sigma_ax = 0.5*(sigma_a + sigma_x);
75 const double T_scal_x = 1.15*Tb_x;
76 const double T_scal_ax = std::sqrt(T_scal_a*T_scal_x);
78 const Evaluation& T_star = max(temperature/T_scal_ax, 1e-5);
80 const Evaluation& Omega = 1.06036/pow(T_star, 0.1561) + 0.193/exp(T_star*0.47635)
81 + 1.03587/exp(T_star*1.52996) + 1.76474/exp(T_star*3.89411);
82 const double B_ = 0.00217 - 0.0005*std::sqrt(1.0/M_a + 1.0/M_x);
83 const double Mr = (M_a + M_x)/(M_a*M_x);
85 *(B_*pow(temperature,1.5)*std::sqrt(Mr))
86 /(1e-5*pressure*std::pow(sigma_ax, 2.0)*Omega);