Numerical Study on the Temperature Profiles and Degree of Burns in Human Skin Tissue during Combined Thermal Therapy

In this study, the temperature distribution in human dermal tissues and possible burns as a result of local heating of the skin were analyzed numerically. In order to obtain the temperature profiles of the dermis, fat, and muscle layers, we solved the Pennes bio-heat equation whose source term was for heat exchange between blood and tissues. The degree of each burn was predicted by an Arrhenius-type damage function. Two boundary conditions, namely constant heat flux and constant temperature, were considered as heating methods. Skin temperature regulation by on/off repetition of heat flux was also considered as a boundary condition. Time-dependent increases in tissue temperature under constant heat flux were determined for the skin. Temperature profiles showed different slopes at each layer due to different thermophysical properties and blood perfusion. Constant temperature heating up to 320 K for 10 minutes did not cause a burn injury according to our results. The results also showed that burns can be avoided by controlling the skin temperature under 320 K. Taken together, our results showed that a high heat flux over a short heating period is safer than a low heat flux over a long heating period.