Unsteady Features of Flow Past a Cavity

by Donald Rockwell, Prof.; Mech. Engrg. and Mechanics, Lehigh Univ., Bethlehem, Pa.,
Charles Knisely, Research Asst.; Mech. Engrg. and Mechanics, Lehigh Univ., Bethlehem, Pa.,

Serial Information: Journal of the Hydraulics Division, 1979, Vol. 105, Issue 8, Pg. 969-979

Document Type: Journal Paper


Measurements of the distributions of total turbulence intensity across the shear layer and corresponding power spectra reveal that the presence of the impingement edge of the cavity decreases the total turbulence intensity by as much as 50% to 80% relative to the case of no edge; this decrease in total intensity is associated with the appearance of well-defined peaks in the power spectrum and a reduction in background turbulence level both at and upstream of impingement. Development of the flow downstream of the impingement edge of the cavity is characterized by a decrease in the maximum value of total turbulence intensity and drastic variations in shapes of the mean velocity and turbulence intensity distributions of the boundary layer. Flow visualization at lower speeds suggests that these characteristics are associated with the distortion of large scale vortical structures convected along the wall downstream of impingement.

Subject Headings: Turbulence | Rivers and streams | Boundary layers | Unsteady flow | Cavitation | Power transmission | Power spectral density | Velocity distribution

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