DRAG OF FREE-FALLING SPHERES IN DILUTE AQUEOUS SOLUTIONS OF POLY(ETHYLENE OXIDE) FOR REYNOLDS NUMBERS ABOVE THE CRITICAL VALUE.
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Drag of free-falling spheres in water and in dilute aqueous solutions of polyethylene oxide was measured by ejecting the spheres near terminal velocity in a fluid-filled tank. Polymer additive concentrations tested were 1000 wppm, 200 wppm, and 100 wppm. The results agree with previous investigations, available only for subcritical Reynolds numbers, in that the drag coefficient decreases with increasing water Reynolds number and decreasing polymer concentration. It is shown that in the polymer solutions abrupt decrease in drag coefficient occurs at about the same Reynolds number 300,000 as the critical value in water. For Reynolds numbers greater than the critical value, the drag was still less than in water and increased slightly with increasing polymer concentration. At Reynolds numbers between 7 and 800,000, the drag coefficients for all polymer concentrations, including water, abruptly increased to nearly a common value at the upper limit of this investigation. Author
- Marine Engineering
- Fluid Mechanics