Generalization of the Weinbaum-Jiji bioheat equation and studies of whole limb heat transfer.
Item
-
Title
-
Generalization of the Weinbaum-Jiji bioheat equation and studies of whole limb heat transfer.
-
Identifier
-
AAI9029993
-
identifier
-
9029993
-
Creator
-
Zhu, Min.
-
Contributor
-
Advisers: Sheldon Weinbaum | Latif M. Jiji
-
Date
-
1990
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Engineering, Mechanical | Engineering, Biomedical
-
Abstract
-
In this dissertation the Weinbaum-Jiji bioheat equation (1985) is generalized to vessels of unequal size and then combined with a new theory for asymmetric countercurrent heat transfer to develop a three-dimensional variable geometry model for whole limb heat transfer. An experimental study is also conducted to verify the predictions of this theoretical model and to provide the input values for model parameters for a human arm.;A brief introduction to blood-tissue heat transfer is given in Chapter 1. In Chapter 2 an asymptotic analysis is derived to elucidate the relationship between the near field temperature of an unequal artery-vein pair and the local average tissue temperature. This analysis is used to rigorously prove the closure approximation relating the local arterial-venous temperature difference and the mean tissue temperature which had been derived by Weinbaum & Jiji (1985) using a more heuristic approach. Based on these results, the Weinbaum-Jiji bioheat equation is generalized for vessels of unequal size.;In Chapter 3 a three dimensional approximate analytic solution technique is developed for treating unequal countercurrent heat exchange. The solution describes the heat transfer between parallel paired countercurrent vessels with a laminar velocity profile asymmetrically embedded in a long cylinder with surface convection. In Chapter 4 this solution is extended to formulate a three dimensional variable geometry model for whole limb heat transfer. This model is not limited by the restriction in the model by Song et al. (1988) which assumes that the heat loss to the surroundings is small compared to the heat exchange between the central vessels. The local microvascular temperature field in the muscle tissue is described by a new approach in which the Pennes (1948) and Weinbaum-Jiji equations are applied in different flow regions. This model also allows for an arbitrary axial variation of the cross-sectional area and blood distribution between the muscle and cutaneous tissue. Furthermore, the computational time for the present model is much shorter than that of the model by Song et al. (1988). Representative solutions for the axial variation of the average skin and central artery and vein temperatures are in much better agreement with available experimental data than previous solutions.;In the experimental study described in Chapter 5, a plethysmographcalorimeter apparatus has been constructed to measure the blood flow rates of the human arm and hand and the heat loss of the hand. The relationship between blood flow and heat transfer when the hand is placed in a water bath at different temperatures is examined. Also, the skin surface temperature distribution of the arm is measured and compared with the theoretical predictions of the whole limb model described in Chapter 4.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
