Transverse Vorticity Measurements in the Wake of an Inverted Oscillated D-Shaped Cylinder
An oscillating inverted D shaped obstruction has been used to provide a well defined vortex street at Reynolds number (U0d/v) equal to 23,000. U0 and d are defined in Fig i which also presents a schematic of the flow based upon phase averaged results.
The purpose of the investigation was to compare time resolved transverse vorticity (ωz(t))measurements with the phase (α) averaged velocity [u(x,y,α),v(x,y,α)] measurements and flow visualization observations. It was expected that the latter two would exhibit good agreement. Prior experience with the ωz(t) measurements in planar shear layers, see Foss (1), has shown that flow fields with a single sign of the mean vorticity (≈∂u/∂y) possess vorticity distributions in which the rms values (ωz) are large with respect to the corresponding mean value. Contrary to this is the plausible expectation that vorticity measurements in the large scale vortex motions would exhibit a clearly recognized distribution during the passage of a large scale coherent motion. The subject flow was selected as a paradigm test to examine the relationships between time resolved vorticity and coherent vortex motions.
KeywordsVortex Convection Vorticity
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