Abstract

This thesis reports the findings of exploratory tests performed with oil vortices produced inside a partially filled cylindrical tank with a rotating base. Three different liquids i.e. Spindle (22.69 cSt), H-22 (46.8 cSt) and H-32 (64.75 cSt) oils are used as the working fluid. The tests are conducted under relatively shallow liquid conditions with heights of 8, 10, and 12mm. The present observations show that the topology of the emerging equilibrium states in oils exhibits a considerably richer morphology than that of water. During a quasi-static spin-up and spin-down of the flow, states ranging from N = 2 to 19 are discovered. Also pulsating (N = 0) and wobbling (N = 1) modes are also detected. In the case of H-22 a retrograde pentagonal (N = 5) equilibrium state is found to materialize. Both the spin-up and spin-down tests are marked with strong hysteresis where in some sectors of the state manifold flow bifurcations exist. These are more prominent in the Spindle Oil than in both H-22 and H-32. In addition, for this oil, the equilibria first appear at lower disk speeds than in H-22 and H-32.
A procession of one or a group with more than one (up to 6) solitary waves arranged symmetrically in a circle around the vortex pattern, moving at higher speeds than the fluid, are identified.
Finally, pattern lock-in is found to occur at a frequency of about one-tenth the frequency of the rotating disk. Having a coefficient of variation less that one, the one-tenth value is deemed to be acceptable.