Interaction of short pulse collimated irradiation with inhomogeneity: An accurate model

The accurate formulation of radiative source is established with the transient effect of radiation transport for evaluating the correct thermal damage in the proximity of laser source. The accurate formulation of radiative source consists of two parts: the conventional absorption term and the propagation term. The inclusion of the propagation term significantly deviates the energy distribution from earlier steady state radiative source especially in the ultrashort time scale where this term has significance. In the present work, this effect has been investigated in the presence of absorbing, emitting, and anisotropically scattering medium within a two-dimensional rectangular domain subjected to collimated irradiation at one of its boundaries. A small inhomogeneity is taken at the center of the top wall which is irradiated with a laser source. The effects of optical parameters such as absorption coefficient, scattering coefficient, and scattering albedo on the temperature distribution in the medium are analyzed. It is found that the modified radiation energy flux gives an early signal of crossing the thermal damage threshold temperature surrounding the inhomogeneity. Inclusion of propagation term in radiation energy source helps to precisely access the extent of thermal damage surrounding the inhomogeneity which is not traceable as per the existing models.