Untitled in english

Author(s)

Maurício Silva Ferreira

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Escola Politécnica (EP/BC)
• Defense date: 2001-12-17

Examining board members

Jurandir Itizo Yanagihara; Marcos Pinotti Barbosa; Agenor de Toledo Fleury; Arlindo Tribess; Takashi Yoneyama

• Advisor: Jurandir Itizo Yanagihara

Abstract

This research presents the development of a model of the human thermal system. Models of this type have applications in several areas, including: the evaluation of thermal comfort, the study of the body\'s temperature regulatory system behavior, and the development of medical equipment. The model can be divided in two parts: the passive system, which is described by the equations resultant from the application of energy and mass balances to the tissues, and the temperature control system, which is responsible for the maintenance of the human body\'s temperature. The passive system includes heat conduction in three dimensions, heat transfer between blood and tissue, heat transfer between large arteries and veins, and heat transfer in the respiratory tract. The model is composed by 15 cylindrical elements representing the body\'s segments: head, neck, trunk, arms, forearms, hands, thighs, legs and feet. The cylinders have elliptical cross sections. This has not been done before, and it is one of the distinguishing features of the model. The partial differential equations of the passive system were solved by the finite-volume method, using a numerical procedure especially developed. The control system includes the vasomotor and \"sudomotor\" responses, and the heat generation due to shivering. In addition, the model is very flexible, which allows its use in many applications. This is possible because of the model computer implementation, which uses object-orientedprogramming. The research presents a thermal neutrality simulation, several transient simulations of abrupt exposures to cold and hot environment, and the comparison of these results with experimental data. Finally, it brings out the importance of human thermal system modeling in the study of the body\'s temperature regulatory system behavior. (AU)