Some Streamwise Vorticity Characteristics of Coherent Structures
A new probe — which measures the streamwise vorticity component, ωx, and all three velocity components, Ū + u, v, w - was used to recognize and analyse coherent structures quantitatively in a fully-developed, turbulent, channel flow. A quadrant analysis was applied to classify events related to the four possible combinations of signs of u and v. To isolate the most energetic events a threshold was introduced in the instantaneous value of the Reynolds shear stress. It was found that the ejections provided the major contribution to ωx 2 regardless of the threshold and distance from the wall. Information on the scales of detected events is also given.
KeywordsCoherent Structure Reynolds Shear Stress Autocorrelation Coefficient Horseshoe Vortex Wall Distance
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- 4.Kovasznay, L.S.G.,1954 Physical measurements in gas dynamics and combustion, Princeton University Press, Princeton, p. 227.Google Scholar
- 5.Corrsin, S. and Kistler, A.L.,1955 NACA Rep. 1244.Google Scholar
- 6.Willmarth, W.W.,1976 Structure of turbulence boundary layers, Advances Applied Mechanics, Vol. 15 Academic Press.Google Scholar
- 9.Kastrinakis, E.G. and Eckelmann, H. Measurements of streamwise vorticity fluctuations in a turbulent channel flow, submitted for publication to J. Fluid Mech.Google Scholar
- 13.Comte-Bel1ot, G., Sabot, J. and Saleh, I., 1978 Proc. Dyn. Flow Conference, Marseille-Baltimore, 213.Google Scholar
- 20.Smith, C.R., Schwartz, S.D., Metzler, S.D. and Cerra, A.W.,1980 Proc. Int. Symp. on Flow Visualization, Bochum, Germany.Google Scholar