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Numerical Investigation of Non-Fourier Heat Conduction in Human Skin

Hodjat, Reza | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 42917 (58)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Taghizade Manzari, Merdad; Sani Joushaghani, Mahdi
  7. Abstract:
  8. When classical Fourier law of heat conduction is not applicable due to finite speed of heat propagation in a medium, non-Fourier heat conduction is used. In non-Fourier heat conduction, heat transfer is studied considering finite speed of heat flux (thermal wave) or temperature gradient or both (dual phase lag). Biological tissues like skin are one of the materials which show non-Fourier behavior during usual heating processes. In this research heat transfer in human skin is modeled by Fourier, thermal wave and dual phase lag (DPL) models. The equations are solved using the finite difference method and the temperature distribution across the tissue is calculated. In thermal wave model, shocks are observed in the result. Hence, artificial viscosity is added to the discretized equation which attenuated the oscillations but did not fully remove them. In Fourier and DPL models, the finite difference solution for temperature distribution in the skin had no oscillations. When the temperature of the skin at the location of pain sensors rises above the pain threshold, a signal is transmitted to the brain and thermal pain is sensed. This transmission occurs in two steps. In the first step a generating current is created. This current is a function of temperature and is modeled by an exponential function. In the second step, generating current initiates a repetitive action potential. A revised version of Hodgkin-Huxley model is employed to simulate the action potential. The frequency of spikes of action potential is a measure of pain intensity. In this work, this frequency is calculated by counting the number of sign changes of membrane potential in the selected time steps. The results show that the fastest heat transfer and most intensive pain occur in the Fourier model of heat conduction
  9. Keywords:
  10. Numerical Solution ; Human Skin ; Non-Fourier Heat Conduction ; Laser Therapy

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