Function opensn::PackGroupsetXS

Defined in File acceleration.h

Function Documentation

std::map<unsigned int, Multigroup_D_and_sigR> opensn::PackGroupsetXS(const BlockID2XSMap &blkid_to_xs_map, unsigned int first_grp_index, unsigned int last_group_index, double time_absorption_scale = 0.0)

Makes a packaged set of XSs, suitable for diffusion, for a particular set of groups.

time_absorption_scale is 1/(theta dt) for a time-dependent problem and 0 otherwise. The time absorption tau_g = 1/(v_g theta dt) is added to the removal cross section and to the transport cross section in the diffusion coefficient, D_g = 1/(3 (sigma_tr,g + tau_g)).