Showing papers by "Young I. Cho published in 1989"

The hydrodynamics of a bent cylinder in a viscoelastic fluid

Abstract: The hydrodynamics of a bent cylinder specimen moving in a viscoelastic fluid and a Newtonian fluid has been studied experimentally by observing the falling motion of the specimen with different initial orientations. The effect of the end-to-end distance on the terminal velocity of the specimen was also investigated in both fluids. In the Newtonian fluid, no matter what the initial position or the bend angle of the specimen was, it always reoriented to the open-end-up position and kept this shape while it fell. In the viscoelastic fluid, however, the open-end-up specimen always fell down as it was, while open-end-down specimen did not always flip to the open-end-up position as in the Newtonian fluid, but, if the bend angle was smaller than a critical value, it fell down with open-end-down shape. The effect of the end-to-end distance on the specimen terminal velocity was found to be significantly different between the Newtonian and the viscoelastic fluid. These observations represent new experimental findings, unique to a viscoelastic fluid, and may be attributed to the existence of a polymer network in viscoelastic solutions created by high molecular-weight polymer chains.