Analysis of fluid mechanics, mass transfer, and solidification in porous media with semipermeable membrane

This dissertation attempts to analyze two phases of the cryopreservation protocol: (1) the introduction of cryophylactic agents (CPAs) and (2) the freezing process and damage mechanism associated with the process.;For the introduction of cryophylactic agents, a one-dimensional analysis for fluid flow and mass transfer is presented for a typical blood vessel-tissue unit. This analysis incorporates concepts of irreversible thermodynamics to model fluid flow across the cell membrane. Next, a multidimensional analysis is performed for a microcirculatory unit of the liver, the hepatic acinus. A theoretical analysis of the fluid flow and mass transfer process in the unit is presented. The complexity of the fluid flow in the vasculature is overcome by applying principles from porous media theory. The numerical simulation of the governing equations is performed utilizing the finite element method. The analysis incorporated Fick's Law in order to test the effectiveness of the model to simulate transport of chemical species in the liver. To model the introduction of cryophylactic agents in the multidimensional system, again concepts from irreversible thermodynamics theory are incorporated.;The next phase of the dissertation presents results from the experimental analysis of the freezing process in liver tissue. This phase of the work is divided into two parts. The controlled freezing utilized a specialized cryomicroscope stage. In uncontrolled freezing, a cryoprobe cooled with liquid nitrogen is used. A low temperature scanning microscope (LTSEM) is utilized to examine both sets of frozen hydrated tissue.;The results from the controlled freezing experiments provided insights into understanding the freezing process and damage mechanism for cooling rates ranging over four orders of magnitude. The structure of the tissue changes dramatically as a function of these rates. The results from the uncontrolled freezing of tissue produced a qualitative relationship between cooling rates and distances from the cryoprobe surface. (Abstract shortened with permission of author.).