66 static Evaluation
gasDiffCoeff(Evaluation temperature, Evaluation pressure)
71 temperature = max(temperature, 1e-9);
72 temperature = min(temperature, 500.0);
73 pressure = max(pressure, 0.0);
74 pressure = min(pressure, 1e8);
78 const double Tb_x = 412.9;
79 const double Tb_w = 373.15;
80 const double V_B_w = 18.0;
81 const double sigma_w = 1.18*std::pow(V_B_w, 0.333);
82 const double T_scal_w = 1.15*Tb_w;
83 const double V_B_x = 140.4;
84 const double sigma_x = 1.18*std::pow(V_B_x, 0.333);
85 const double sigma_wx = 0.5*(sigma_w + sigma_x);
86 const double T_scal_x = 1.15*Tb_x;
87 const double T_scal_wx = std::sqrt(T_scal_w*T_scal_x);
89 const Evaluation& T_star = max(temperature/T_scal_wx, 1e-5);
91 const Evaluation& Omega = 1.06036/pow(T_star, 0.1561) + 0.193/exp(T_star*0.47635)
92 + 1.03587/exp(T_star*1.52996) + 1.76474/exp(T_star*3.89411);
93 const double B_ = 0.00217 - 0.0005*std::sqrt(1.0/M_w + 1.0/M_x);
94 const double Mr = (M_w + M_x)/(M_w*M_x);
96 *(B_*pow(temperature,1.6)*std::sqrt(Mr))
97 /(1e-5*pressure*std::pow(sigma_wx, 2.0)*Omega);