Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : November 07, 2019 - November 08, 2019
The flow of viscoelastic fluids in an annular space between a rotating corrugated inner cylinder and a stationary outer cylinder, in which shear waves propagate, is studied. The fluids used are aqueous cetyltrimethylammonium bromide (CTAB) solution with sodium salicylate (NaSal) as added salt. The velocity fields are measured using a particle image velocimetry (PIV). Three different types of mean flow profiles are observed between the cylinders with a radius ratio of 0.178, depending on the rotational speeds of the inner cylinder. The different types include (a) Couette flow like profiles, (b) profiles having the maximum between the cylinders, and (c) profiles with small slopes. Type (a) profiles appear at lower rotational speeds, and type (c) profiles appear at higher rotational speeds. The results show that the high-speed streaks appear on the surface of the inner cylinder, and the radial extent of these high-speed streaks can be seen to determine the mean flow profiles between the cylinders. The experimental results with different concentrations of CTAB/NaSal suggest that the critical values of the rotational speed at which the flow type changes depending on the shear wave speed of the fluid.
