Date of Award

Spring 1980

Document Type

Dissertation

Degree Name

Doctor of Engineering Science in Chemical Engineering

Department

Chemical Engineering and Chemistry

First Advisor

Ching-Rong Huang

Second Advisor

Hung T. Chen

Third Advisor

David S. Kristol

Fourth Advisor

James L. Martin

Fifth Advisor

Angelo J. Perna

Abstract

The flow behavior of human blood is an important facet of the circulatory system as it affects all of the organs of the body. The rheological properties of whole blood provide a means of analyzing the flow of red cells and plasma through the microcirculation. A recently observed rheological characteristic of whole human blood is thixotropy, a time-dependent phenomenon. This phenomenon is caused mainly by the redistribution of an aggregated form of erythrocytes, known as rouleaux, and the non-aggregated, single erythrocytes. In order to further define and analyze the thixotropic properties of blood, the Huang model is used to quantitatively characterize the rheological behavior and relate recorded alterations in blood viscosity at low shear rates to the biophysical parameters of blood elements. Analysis of the various parameters defined by the rheological equation is used to characterize the flow properties of whole blood and provide quantitative comparison among blood samples under a variety of clinical conditions.

Rheological determinations and standard clinical hematological evaluations were performed on sixteen normal subjects and compared with similar data obtained from patients suffering from either polycythemia, Parkinson's disease, or hypertension. In addition, the data of thirteen normal males was compared to that of a group of apparently healthy males who exhibited high levels of one or more of the following coronary risk factors: cigarette smoking, serum cholesterol and diastolic blood pressure. Data analysis for the sample groups was performed for the mean and variance of the group value. Analysis of variance was performed using the standard F-test, and the Student t-test for small sample sizes was used to test for significance in the difference of means.

An analytical solution of the Navier-Stokes equation is presented for the case of a transient flow curve using a Couette geometry. Analysis of the solution indicates that it is possible for a Newtonian fluid to exhibit a hysteresis loop effect in its flow curve under certain experimental conditions. The size and shape of the generated loop was found to be controlled by a dimensionless group. This analysis can be used to detect and eliminate the presence of any artificial hysteresis loop effects such that the true non-Newtonian behavior of a material may be examined.

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