Experimental investigations of the transport properties of flow suspensions : I. Measurement of velocity distributions of suspension flows in a rectangular channel. II. Experimental study of the effective thermal conductivity in shear flow of a suspension. III. The use of fluorescence correlation spectroscopy to measure molecular diffusion and velocity distributions

• Main Author: Chung, Ernest Ying-Chee
• Format: Others
• Language: en
• Published: 1980
• Online Access: https://thesis.library.caltech.edu/4072/1/Chung_eyc_1980.pdf; Chung, Ernest Ying-Chee (1980) Experimental investigations of the transport properties of flow suspensions : I. Measurement of velocity distributions of suspension flows in a rectangular channel. II. Experimental study of the effective thermal conductivity in shear flow of a suspension. III. The use of fluorescence correlation spectroscopy to measure molecular diffusion and velocity distributions. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/k2rw-rc28. https://resolver.caltech.edu/CaltechETD:etd-10132006-090651 <https://resolver.caltech.edu/CaltechETD:etd-10132006-090651>

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. This study was directed towards the understanding of transport properties of flowing suspensions. The first part of the thesis detailed the experimental study undertaken to investigate the characteristics of flowing suspensions. An experimental method capable of measuring the velocities of both the dispersed and suspending phases of a flowing suspension was first developed. The method was shown to be capable of measuring the velocity distributions of moderately concentrated suspensions. By using a modified laser Doppler anemometer, the velocity distribution of the suspended fluid was approximated by measuring the velocity of small fluorescent tracers, while the scattered signal from the suspended particles gave a direct measurement of their velocity distribution. Suspensions of rigid latex spheres, red blood cells, and ghost red blood cells were used. The observed behavior of the different suspensions were similar. However, the behavior of suspensions of rigid latex spheres showed a stronger dependence on the concentration of suspended particles, and a dependence on flow rates which was not observed with suspensions of ghost cells. The second part of the thesis describes the measurements of the effective thermal conductivity of sheared suspensions of rigid spherical particles. The objective was to verify the theoretical prediction of Leal (1973) for a dilute suspension undergoing shear at low particle Peclet number, and to extend the range of the experiments to conditions beyond the scope of the theory. Surprisingly, reasonable agreement with the theoretical prediction was observed even for suspensions of moderate concentrations ([...] 0.25) and higher Peclet numbers: (Pe ~ 0(1)). The trend of the data, however, verifies the obvious fact that the theory does not completely describe the transport behavior at higher concentrations and Peclet numbers. The range of quantitative applicability of Leal's result is apparently only for Pe < 0.01 and [...] < 0.01, but the changes in the effective thermal conductivity in this domain were too small to be measured in our apparatus. In the third part of the thesis, an analysis on the use of fluorescence correlation spectroscopy to measure molecular diffusion and velocity distributions in a sheared flow is presented. The superior spatial resolution of the method allows local measurements of molecular diffusion and/or velocity distributions. The method can also be used to measure self-diffusion of the suspended particles in a sheared suspension.