The oscillatory forces on a semi-submerged circular cylinder in water and in dilute aqueous solution of poly (ethylene oxide).

Abstract

The oscillatory forces on towed semi -submerged rigid circular cylinders were measured in water and in 100 and 200 ppm aqueous solutions of Polyox WSR301 . Cylinders of half-, one-, and two-inch diameters were towed in a small circular towing-tank and the hydrodynamic forces sensed by a strain gauge and analyzed for the time-dependent frequency spectra. The towing speeds ranged from 59 cm/sec to 253 cm/sec corresponding to Reynolds Numbers from 4 5 2x10 to 1x10 . The Strouhal Numbers based on the dominant frequency of the oscillatory lift were between 0.17 and 0.21 and are in agreement with the existing data for a completely submerged circular cylinder. These frequencies were not influenced by either the air-water interface or the addition of drag reducing polymers. Also independent of the polymer concentration was the amplitude of the life force. Attempts to interpret the oscillatory drag component proved inconclusive.