초록
As a simplified model for the motion of fibers in polymeric fluids, we investigated experimentally the file falling behavior of a cylindrical slender body in stationary polymer solutions by the use of multi-stroboscopic photographing technique and developed a new analysis method to evaluate the actual falling characteristics of a body. Main findings obtained from this study can be summarized as follows : (1) A slender body falling in polymer solutions rotates its attitude into vertical direction and moves translationally maintaining a constant inclination angle (final orientation angle or steady angle). (2) Both the horizontal and vertical velocities of a body become larger in the more dilute polymer solutions. (3) The larger the concentration of the solutions, the smaller inclination angle at which the maximum angular velocity takes place. (4) The final orientation angle of a body becomes smarter as the solution concentration is increased. (5) A new mechanism combining the shea-thinning and elastic properties of non-Newtonian viscoelastic fluids as well as a supercritical flow theory around a body can be used to interpret the reason for our findings.
