A frequency-based numerical approach for unsteady radiative transfer in participating media

The one-dimensional transient radiative transfer problem in the Cartesian coordinate system - an absorbing and scattering medium illuminated by a short laser pulse - is solved by the use of a discrete ordinates-finite volume method. Previous works have shown that the original numerical approach, based in the space-time domain, induces transmitted flux emerging earlier than the minimal time required by the radiation to leave the medium. Therefore, a frequency-based numerical method is formulated, implemented, and validated in this paper. Results for transmittances are accurate, without physically unrealistic behaviors at early time periods. However, the frequency-dependent approach is computationally expensive; it requires approximately five times more computational time than its temporal counterpart. Ongoing research is devoted to the optimization of these CPU requirements.