Modeling the temperature changes of skin cover in the process of cryotherapeutic exposure
The results of numerical modeling the distribution of temperature fields and heat fluxes in the skin of a person during the general therapy action are presented. The results were obtained using a mathematical model of heat exchange between the flow of a gaseous medium (liquid nitrogen vapour) and a biological object (a patient of general therapeutic effect) in a three-dimensional nonstationary formulation. The study was carried out using the finite element method in the Comsol Multiphysics application package. The model included layers of biological tissue (epidermis, dermis, internal tissue, subcutaneous layer) and air medium (nitrogen vapors). Calculations of heat transfer processes in biological tissue were performed using the Bioheat Transfer module. In the heat equation the heat of human biological tissues was taken into account. The flow of gaseous nitrogen was considered to be laminar one. Laminar flow calculations were performed in the Laminar Flow module and described by the Navier-Stokes equation. Two modules were combined by Comsol Multiphysics. To check the convergence of the results the model is analyzed by the built-in tools for assessing the quality of elements. In the calculations all materials are assumed to be isotropic. The created non-stationary computer model allows describing the distribution of thermal fields in the skin integument during the general therapy action. The results obtained can be applied when modernizing cryochamber regimes and designing new cryochamber with improved cryotherapy effect without any harm to the patient.