Free Surface on a Simple Fluid between Cylinders Undergoing Torsional Oscillations. IV. Oscillating Rods

In earlier papers (Parts I and II) we gave the perturbation analysis for the prediction of the free surface on a simple fluid near an oscillating rod and presented the results of a preliminary experiment involving a single rod in one sample of simple fluid. In this paper we report the results of a recent more extensive experimental investigation aimed at testing the predictions of the theory. These experiments involve the use of two different simple fluids and three rods of differing diameters. The experimental results reinforce our earlier results and substantiate the predictions of the theory with respect to the diameter dependence of the normalized height of climb at the rod surface. The rapid increase in fluid temperature near the rod caused by shear heating is illustrated, and the asymptotic form of the theory for large angular frequencies is derived.