Drag of a sphere in dilute polymer solutions in high Reynolds number range |
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Authors: | K Watanabe Hiroto Kui Ikumi Motosu |
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Institution: | (1) Department of Mechanical Engineering Tokyo Metropolitan University Hachioji, Tokyo 192-0397 Japan, JP |
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Abstract: | We have measured by means of four ultrasonic transducers the fall velocity of a sphere at high Reynolds number range in dilute
polyacrylamide solutions which have viscoelastic effects. The polymer solutions were 5, 20 and 50ppm in the concentration.
Basset-Bousinessq-Oseen equation for the falling sphere was analyzed numerically on Newtonian fluids in order to compare with
the fall velocity of a sphere in the polymer solutions, and the experimental data of the fall velocity in tap water is in
agreement with the range of no effect of the test tank wall. In polymer solutions, it was shown that the fall velocity is
larger than that in Newtonian fluids within the critical Reynolds number range such that the drag reduction occurs and is
smaller than that of Newtonian fluids over the range. The experimental data for the drag reduction ratio of polymer solutions
is arranged by Weissenberg number calculating the experimental data of the first normal stress differences. It was shown
that the maximum drag reduction ratio in the polymer solutions lies in the range of We=3∼10.
Received: 15 October 1997 Accepted: 12 May 1998 |
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Keywords: | Drag of sphere drag reduction polymer solution |
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