To understand thermal comfort and develop practical ways to keep the body at the right temperature in different situations, we must look into how heat moves through human skin. Pennes’ 1948 bioheat equation is a complete way to study how heat moves through living cells because it considers metabolic heat production and blood flow. This model will look at things like the thickness of the skin, its ability to transfer heat, the rate of blood flow, the amount of heat made by metabolism, the ambient temperature, and the air speed. Given the bioheat equation, a numerical paper titled “ Heat Transfer Model to Predict Human Skin Temperature under Comfort Level by using Bioheat Equation” has executed a study, which is our reference paper for validating results of sun irradiation on human skin.

Figure 1: Mathematical simplification for modeling sun irradiation on human skin , given in the reference paper

Simulation Process

The initial human skin layers were designed using Design Modeler and then discretized by only 900 structured cells. The transient (unsteady) formulation provides a setup that can predict heat transition through human skin layers. The radiative sun irradiations are applied to the skin`s surface by the Discrete Ordinates radiation model.

Post-processing

The contour shows very vividly how the temperature changes across the layers of human skin when exposed to the sun. With temperatures range from 32.5°C to 36.8°C, this gradient does a good job of showing how heat is spread. The simulation shows how solar radiation affects different areas of skin by simulating the complicated process of heat transfer inside the skin. Regarding validation, the reference paper says the skin temperature is 36.2°C, but the CFD model says it is 34.7°C. Given how complicated bioheat modelling is, this 1.5°C difference (about 4.1% lower) shows a good overall agreement. The difference could be because of different assumptions about the skin’s properties, the environment, or the model’s physiological reactions.