Ecole Navale, France
I would like to congratulate the authors for their fine work and the beauty of the visualizations. I have a question concerning the behavior of the visualizing fluid. Because of its properties (visoelastic) the fluid will be reusable to the deformation intensity, that is to say to a time scale proportional to the length scale (L) divided by the velocity scale (V), i.e. L/V. Therefore, the visualization of different length scale models operating at equal Reynolds (v VL) numbers will (or may) be quite different. What is your opinion about this?
We appreciate the comments and concerns from a very distinguished scholar in the field of viscoelastic flows.
All experiments in which we have had an opportunity to compare our flow visualization results with those of other workers, show very similar visualization patterns. Hence we think the tracer is responding to the length scales in the main body of the flowing liquid (water) rather than scales determined by the tracer itself.
In studies of flow around circular cylinders (Hoyt and Sellin (15)), various size cylinders gave very similar Kármán vortex patterns at the same Reynolds numbers (even though the vortex shedding frequency changed substantially as the cylinder size was changed).
In preparing the reply to discussion of our paper, we discovered that we had omitted references in the text to our previous papers on the topic, and take this opportunity to add a few of the more recent.
15. Hoyt, J.W. and Sellin, R.H.J. “A Flow Visualization Study of Separated Flow over Circular, Elliptical and Square Cylinders” in M.V.Otugen, et al., eds. Separated and Complex Flows—1995, ASME FED-Vol. 217, 1995, pp. 115–120.
16. Hoyt, J.W. and Sellin, R.H.J. “Flow Over Tube Banks—A Visualization Study,” Journal of Fluids Engineering, Vol. 119, 1997, pp. 480–483.
17. Hoyt, J.W. and Sellin, R.H.J. “3-D Visualization of Flow Past Intersecting Cylinders,” Proc. ASME Fluids Engineering Division, Summer Meeting 1998 (on disc), Washington, D.C. Paper No. FEDSM-5269, 1998.
18. Hoyt, J.W. and Sellin, R.H.J. “A Mirror and Tracer Method of 3-D Flow Visualization,” Proc. 8th International Symposium on Flow Visualization (1998) (on disc), Sorrento, Italy. Paper No. 2, pp. 2.1–2.6, 1998.