transient_source_function.cc

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#include "transient_source_function.h"
 
//###################################################################
/**Constructor for the transient source function. The only difference
 * as compared to a steady source function is the treatment of delayed fission.*/
lbs::TransientSourceFunction::
TransientSourceFunction(const LBSSolver& lbs_solver,
                        double &ref_dt, chi_math::SteppingMethod &method) :
  SourceFunction(lbs_solver),
  dt_(ref_dt),
  method_(method)
{}
 
//###################################################################
/**Customized delayed fission source..*/
double lbs::TransientSourceFunction::
AddDelayedFission(const PrecursorList &precursors,
                  const std::vector<double> &nu_delayed_sigma_f,
                  const double *phi) const
{
  const auto& BackwardEuler = chi_math::SteppingMethod::IMPLICIT_EULER;
  const auto& CrankNicolson = chi_math::SteppingMethod::CRANK_NICOLSON;
 
  double theta;
  if      (method_ == BackwardEuler) theta = 1.0;
  else if (method_ == CrankNicolson) theta = 0.5;
  else                              theta = 0.7;
 
  const double eff_dt = theta * dt_;
 
  double value = 0.0;
  if (apply_ags_fission_src_)
    for (size_t gp = first_grp_; gp <= last_grp_; ++gp)
      if (gp < gs_i_ or gp > gs_f_)
        for (const auto& precursor : precursors)
        {
          const double coeff =
            precursor.emission_spectrum[g_] *
            precursor.decay_constant /
            (1.0 + eff_dt * precursor.decay_constant);
 
          value += coeff * eff_dt *
                   precursor.fractional_yield *
                   nu_delayed_sigma_f[gp] *
                   phi[gp] /
                   cell_volume_;
        }
 
  if (apply_wgs_fission_src_)
    for (size_t gp = gs_i_; gp <= gs_f_; ++gp)
      for (const auto& precursor : precursors)
      {
        const double coeff =
          precursor.emission_spectrum[g_] *
          precursor.decay_constant /
          (1.0 + eff_dt * precursor.decay_constant);
 
        value += coeff * eff_dt *
                 precursor.fractional_yield *
                 nu_delayed_sigma_f[gp] *
                 phi[gp] /
                 cell_volume_;
      }
 
  return value;
}