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.