A combined particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) system was employed to investigate turbulent mixing in a confined rectangular jet. The Reynolds number based on bulk velocity and hydraulic diameter was 50,000. The Schmidt number for the passive scalar was 1,250. Velocities conditioned on the scalar were evaluated. Since the joint PDF was not jointly Gaussian in this flow, the conditional mean velocity agreed with a linear model only when the mixture fraction is close to the local mean mixture fraction. A gradient PDF model for the conditional velocity was also tested against the experimental data. The model predicted the cross-stream conditional velocity very well, but gave poor predictions for the streamwise conditional velocity. Finally, the scalar fluctuations conditioned on velocity were presented and analyzed against a linear model.
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