A sweating model for the internal ventilation of a motorcycle helmet

We present a thermodynamic model for the evolution of sweat in a porous medium in contact with a part of the human body, capable of describing the evaporation-related heat transfer phenomena. This is suitable for the analysis and optimization of the internal ventilation of a motorcycle helmet, with the purpose of enhancing the comfort and ultimately the safety of the rider. The model is based on a set of evolution equations for the three scalar unknowns temperature, absolute humidity and sweat. Its mathematical properties as well as those of the numerical counterpart are thoroughly investigated, and an efficient solution algorithm is devised. Simulations show the onset of a free-boundary separating the wet and dry regions and highlight the zones where sweat accumulates.