ABSTRAKT

Phenomenon of heat transfer through the body of biological tissue phantoms has been numerically modelled in cylindrical coordinate system. The tissue phantom has been subjected to a train of short pulse laser irradiation. Time history of intensity distribution within the phantom has been determined through FVM-based solution of transient radiative transfer equation (RTE). The solution of RTE has been coupled with one of the most generalised non-Fourier heat conduction models, i.e. dual phase lag (DPL) model to determine the temperature field. The numerical methodology developed has been verified against the results reported in the literature. The DPL-based temperature predictions have been compared with those of Fourier and hyperbolic models. Effects of relaxation times associated with temperature gradient (τ_T) and heat flux (τ_q) have been investigated. Results reveal that non-Fourier models predict substantially higher temperature levels compared to that for the Fourier model. The studies performed to analyse the effects of τ_T and τ_q on temperature response show that τ_q induces wave nature to the thermal fronts propagating in the tissue medium. On the other hand, τ_T tends to smoothen the wave nature of sharp thermal wave fronts induced by τ_q. Effects of absorption inhomogeneity on temperature distributions have been captured quite well. To the best of our knowledge, the work presented is one of the first attempts to develop the cylindrical coordinate system-based numerical methodology for coupling the transient form of RTE to the most generalised non-Fourier model (dual phase lag model) and holds it importance in therapeutic applications of short pulse lasers.