Session MA - Turbulent Boundary Layers V.
MIXED session, Tuesday afternoon, November 23
Grand I, Westin Seattle
Successful measurements (6/03) of (u,v,ømega _z) and (u,w,ømega _y) at y=15cm were obtained at the SLTEST site (Dugway) Utah. A neutral atmosphere for the measurement periods: I-30 and II-25 min. was experienced. A relatively high velocity: \bar u_I =4.9m/s and a low velocity \bar u_II =1.86m/s resulted in y+=2600 and 1100 respectively; k^+\approx 60. (The uncertainty in y+ is estimated at \pm 20%). The ^ \bar u^+,\;\tilde u^+,\;\tilde v^+ and \tilde ømega ^+ values were 18, 2.69, 1.27, 2.07 and 15.8, 2.29, 0.93, 1.61 for the two periods. The influence of the wall is strongly expressed in the vorticity fluctuations: [\tilde ømega _y /\tilde ømega _z ]=0.91 for I and 0.3 for II. The spectra show that the ``loss'' of ømega _y intensity is a result of the steep decrease for k values smaller than from the peak at k\eta =0.2. Similarly, the rhs terms of \-\partial øverline u'v' /\partial y=øverline v'ømega '_z -øverline ømega 'ømega '_y \ change significantly. The ratio: øverline ømega 'ømega '_y /øverline v'ømega '_z is -1.8 for I and -0.043 for II (øverline v'ømega '_z <0). The spectral peaks of these correlations are similar; they show that the peak intensities occur close to the vorticity peaks (k\eta \approx 0.2) vs. the small (2-6\times 10^-3) k\eta velocity peaks.