The behavior of bimodal suspensions of oblate spheroids undergoing simple shearing flow has been described by analyzing the frequency spectra of orientation-dependent macroscopic properties. In particular, the frequency spectra of rheo-optical transients in turbidity and angular light scattering obtained experimentally from mono- and bimodal suspensions of human and frog erythrocytes showed peaks corresponding to the dominant frequencies of the particles in the flow. The method can, in principle, be applied to multimodal dispersions to obtain information on particle geometry. / The effect of high polydispersity on the rheo-optical transients of sheared suspensions have been studied. The time-dependent behavior of such systems is neither determined by the period of rotation defined by the mean axis ratio nor by the mean period of rotation amongst particles, but by the most probable period of rotation (i.e. the value corresponding to the maximum in the distribution of periods of rotations). Rheo-optical transients in polydisperse kaolin (clay) suspensions have been experimentally obtained. Here the oscillations, in contrast to the slightly polydisperse suspensions studied previously, are highly damped. Frequency spectra obtained from these experiments have peaks near 2/T(,m) , where T(,m) is the most probable period in the ensemble. / Finally, the influence of the rotary Brownian motion on the rheo-optical transients of sheared spheroidal suspensions is considered by using simulation procedures such as those employed previously to analyze rheological properties and memory loss. The rotary Brownian motion induced two effects: damping of oscillations and a shift in the extrema of the oscillations resulting in variation in the apparent mean period of rotation. Experiments with human erythrocytes at low Brenner number confirmed such behavior. Also a system with strong rotary Brownian motion was observed for which the rheo-optical transients showed monotonic changes. / The observations made in this work contribute to a better understanding of the transient rheo-optical properties of flowing suspensions.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.68547 |
| Date | January 1980 |
| Creators | Cerda, César Manuel. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Chemistry) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 000128003, proquestno: AAINK51902, Theses scanned by UMI/ProQuest. |
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