New neutrino cooling routine

neutrinos/mod_sneut5.H

@@ -0,0 +1,118 @@
+#ifndef SNEUT5_H
+#define SNEUT5_H
+
+#define _USE_MATH_DEFINES
+
+#include <AMReX_REAL.H>
+#include <AMReX_Array.H>
+
+using namespace amrex;
+
+template <int do_derivatives>
+AMREX_GPU_HOST_DEVICE AMREX_INLINE
+void sneut5(const Real temp, const Real dens, const Real abar,
+ const Real zbar, Real& snu, Real& dsnudt, Real& dsnudd,
+ Real& dsnuda, Real& dsnudz)
+{
+
+Real t9, t8, rho, ep_1, ep_2, w0, gamma, lambda,
+ w1, w2, rho_bar, n_e, mu_e;
+
+t9 = temp * 1.0e-9_rt;
+t8 = temp * 1.0e-8_rt;
+rho = dens;
+snu = 0.0e0_rt;
+mu_e = abar/zbar;
+dsnudt = 0.0e0_rt;
+dsnudd = 0.0e0_rt;
+dsnuda = 0.0e0_rt;
+dsnudz = 0.0e0_rt;
+
+// constants 
+constexpr Real q_e = 4.8032e-10_rt; // Electron charge cm^3/2 g^1/2 s^-1
+constexpr Real m_e = 9.1094e-28_rt; // Mass of electron in g
+//constexpr Real n_e = rho/(m_e * 1.66054e-24_rt);
+//constexpr Real mu_e = abar/zbar;
+constexpr Real hbar = 1.0546e-27_rt; // h/2pi in cm^2 g s^-1
+constexpr Real c = 3.0e10_rt; // speed of light in cm s^-1
+constexpr Real quart = 1.0e0_rt/4.0e0_rt;
+constexpr Real twothd = 2.0e0_rt/ 3.0e0_rt;
+constexpr Real k = 1.3807e-16_rt; // Boltzmann constant cm^2 g s^-2 K^-1
+
+n_e = rho/(m_e * 1.66054e-24_rt);
+// initialize
+// Epsilon (ep_) has units (erg g^-1 s^-1)
+
+Real ep_pair{0.0e0_rt};
+Real ep_pairdt{0.0e0_rt};
+Real ep_pairda{0.0e0_rt};
+Real ep_pairdz{0.0e0_rt};
+
+Real ep_photo{0.0e0_rt};
+Real ep_photdt{0.0e0_rt};
+Real ep_photda{0.0e0_rt};
+Real ep_photdz{0.0e0_rt};
+
+Real ep_plasma{0.0e0_rt};
+Real ep_plasmadt{0.0e0_rt};
+Real ep_plasmada{0.0e0_rt};
+Real ep_plasmadz{0.0e0_rt};
+
+Real ep_brem{0.0e0_rt};
+Real ep_bremdt{0.0e0_rt};
+Real ep_bremda{0.0e0_rt};
+Real ep_bremdz{0.0e0_rt};
+
+if (temp < 1.0e7_rt) return;
+
+// Pair annhilation neutrinos
+// for reactions like e+ + e- => nu + nubar
+// eq 18.81
+if(t9 < 1){
+ ep_pair = (4.9e8_rt/rho) * std::pow(t9,3.0e0_rt) * std::exp(-11.86e0_rt*t9);
+} else if(t9 > 3.0e0_rt){
+ ep_pair = (4.45e15_rt/rho) * std::pow(t9, 9.0e0_rt);
+}
+
+// Photoneutrinos
+// for reactions like 
+// eq 18.82
+ep_1 = 1.103e13_rt * std::pow(rho, -1.0e0_rt) * std::pow(t9, 9.0e0_rt) * std::exp(-5.93e0_rt/t9);
+ep_2 = 0.976_rt * 1e8_rt * std::pow(t9, 8.0e0_rt) / (1.0e0_rt + 4.2e0_rt * t9);
+rho_bar = 6.446e-6_rt * rho * std::pow(t9, -1.0e0_rt) / (1.0e0_rt + 4.2e0_rt * t9);
+ep_photo = ep_1 + ep_2 * 1.0e0_rt/(mu_e + rho_bar);
+
+// Plasmaneutrinos
+// for reactions like gamma_plasm -> nu + nubar
+// eq. 18.83
+w1 = (4.0e0_rt * M_PI * std::pow(q_e, 2.0e0_rt) * n_e)/m_e;
+w2 = 1 + (std::pow(hbar, 2.0e0_rt)/std::pow(m_e * c, 2.0e0_rt)) * std::pow((3.0e0_rt * std::pow(M_PI, 2.0e0_rt) * n_e), twothd);
+w0 = std::sqrt(w1) * std::pow(w2, quart);
+
+gamma = (hbar * w0)/(k * temp);
+lambda = (k * temp)/(m_e * std::pow(c,2.0e0_rt));
+
+// eq 18.85
+if(gamma < 1){
+ ep_plasma = 3.356e19_rt * std::pow(rho, -1.0e0_rt) * std::pow(lambda, 6.0e0_rt) * (1.0e0_rt + 0.0158_rt*std::pow(gamma,2.0e0_rt)) * std::pow(t9,3.0e0_rt);
+} else if(gamma > 1){
+ ep_plasma = 5.252e20_rt * std::pow(rho, -1.0e0_rt) * std::pow(lambda, 7.5e0_rt) * std::pow(t9, 1.5e0_rt) * std::exp(-lambda);
+}
+// Bremsstrahlung neutrinos
+// for large rho
+// eq 18.86
+ep_brem = 0.76e0_rt * (std::pow(zbar, 2.0e0_rt)/abar) * std::pow(t8, 6.0e0_rt);
+
+// the total neutrino loss rate
+
+snu = ep_pair + ep_photo + ep_plasma + ep_brem;
+if constexpr (do_derivatives) {
+ dsnudt = 0;
+ dsnuda = 0;
+ dsnudz = 0;
+ dsnudd = 0;
+} 
+
+}
+
+#endif