Thermal lagging effect on heat transport within living biological tissues

Thermal lagging effect on heat transport within living biological tissues is explored in the context of different relaxation mechanisms. The governing equations of temperature rooted the delay effect between heat flux and temperature gradient, as well as non-equilibrium effect between blood vessel and peripheral tissues, are constructed separately via the classic dual-phase lag model (DPL) and generalized dual-phase lag model (GDPL). An analytical procedure based on the Laplace transform technique and its limit theorem is then proposed. The expressions and effective values of phase lags rooted different effect have been derived and further estimated. On this basis, the temperature response of a biological tissue with its boundary exposed to a pulse heat flux is analyzed. The detailed parametric study has been conducted to explore the dependence of these phase lags on tissue structures and their effect on heat transport properties. The results highlight the contributions of the delay effect and non-equilibrium effect in temperature prediction and state that the delay effect is dominated for a larger tissue size. Meanwhile a significant difference has also been observed with the boundary conditions that obey different thermal conduction mechanism.