Turbulence Effects on Drag of Sharp-Edged Bodies

by John A. Roberson, Prof. of Civ. Engrg. and Res. Engrg.; Albrook Hydr. Lab., Washington State Univ., Pullman, WA,
Chi Yu Lin, Hydr. Engr.; Harza Engineering Co., Chicago, IL,
Scott G. Rutherford, Res. Asst.; Urban Systems Engrg. Center, Northwestern Univ., Evanston, IL,
Marvin D. Stine, Jr. Civ. Engrg. Ofcr.; Moody AFB, Valdosta, GA,

Serial Information: Journal of the Hydraulics Division, 1972, Vol. 98, Issue 7, Pg. 1187-1203

Document Type: Journal Paper


Contrary to popular opinion, wind tunnel tests showed that the drag coefficient of angular shaped bodies is significantly affected by the intensity of the free stream turbulence. For some bodies an increase in intensity causes an increase in CD while for others a decrease in CD results. Tests made on a vibrating body having a shape similar to an H beam showed that the amplitude of vibration was increased more than 200% with an increase in free stream turbulence. The change in coefficient of drag CD is attributed to two primary effects. The first is increased Reynolds stress in the region of the surface of separation which appears to cause an increase in CD and the other is reattachment of the flow to the body which may cause the CD to increase or decrease depending upon the shape of the body. The range of Reynolds numbers in these tests is limited to the relatively narrow span from approximately 5 x 103 to 7 x 104.

Subject Headings: Turbulence | Drag (fluid dynamics) | Rivers and streams | Vibration | Wind tunnel | Tunnels | Reynolds stress | Overland flow

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