The development and structure of Dean vortices in a curved channel were measured and studied. A 40:1 aspect ratio channel with mild curvature was employed. Circulation of mean streamwise vorticity, and maxima of streamwise, spanwise and radial components of vorticity increase as the Dean number increases from 40 to 140. Mean vorticity components were determined from measurements of the three components of mean velocity using a miniature five hole pressure probe. Spectra obtained from a subminiature crossed-wire probe show principal and harmonic frequencies for Dean numbers greater than 165, when vorticies are twisting. Spectral peaks at other Dean numbers provide evidence of oscillations also observed during flow visualization.

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http://archive.org/details/thedevelopmentnd1094523176

Lieutenant, United States Navy