Measurement of Unsteady Flow
Pictures of Vortex Breakdown in a Closed Cylindrical Container
by Scott Harris
Basically, what I have is a quartz cylinder with a rotating lid. Figure 1 gives you an idea of what it looks like. The Reynolds number is Re=Omega R^2/nu. The only other non dimensional ratio needed to completely describe this flow is delta=H/R. Figure 2 shows a graph of the different behaviors this flow can undergo (I scanned this plot from the paper by Escudier ) By measuring the displacement of the lines that I tag into a flow, I can compute velocity data. Some of the things I'm working on related to the flow tagging technique include ray tracing methods to remove distortion in images caused by viewing flows through curved windows, multiple camera techniques to extract three-dimensional data, and techniques to identify lines and use their motion to compute velocities. In the regions of the parameter space (Re, delta) where the flow can be computed accurately, I intend to preform very accurately controlled experiments and compare the PHANTOMM data to computations in order to validate the technique. Then I want to examine new regions of (Re, delta) that have not been previously studied. In particular the transition to turbulence and the departure from axisymmetry.
References  M.P. Escudier. Observations of the flow produced in a cylindrical container by a rotating endwall.
Experiments in Fluids, 2:189-196, 1984.
For more images scroll down this page.
Schematic diagram of my apparatus.
Plot of the different flow regimes in this geometry.
(From the paper by Escudier )
Re=957 and H/R=2.0. Several PHANTOMM
lines tagged at one second intervals.
Note that there is no vortex breakdown.
Re=1897 and H/R=2.0. Two breakdown bubbles
and PHANTOMM lines showing the axial velocity profile
in the region of the lowest bubble.
Re=1813 and H/R=2.0. PHANTOMM lines showing the
velocity profile near the lowest breakdown. The lines
arching near the top of the image have rotated one half
revolution and have re-appeared in the interrogation
Re=1813 and H/R=2.0. PHANTOMM lines tagged below
the lowest bubbles show that the flow is nearing
stagnation along its axis. I'm also working on
computations of this flow.