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In studying scalar transport and mixing by turbulent flows it is not
sufficient to consider only the time-averaged velocity and concentration
fields. The correlations between the velocity and concentration fluctuations
also play an important role in the mean conservation equations that
describe turbulent transport. Experimental characterization of these
correlations is needed for the development and validation of simplified
physical models. By combining laser induced fluorescence (LIF) and molecular
tagging velocimetry (MTV) techniques developed in the Center, we have
devised a novel means to simultaneously measure the velocity and concentration
fields in liquid-phase flows. The example shown here illustrates a two-stream
turbulent shear layer. The combined LIF/MTV diagnostics reveals that
the correlation between transverse velocity and concentration fluctuations
is nearly invariant throughout the mixing zone.
Reference:
"Simultaneous Whole-Field Measurements of Velocity and Concentration
Fields Using Combined MTV and LIF," Koochesfahani, M., Cohn,
R, and MacKinnon, C., Meas. Sci. Technol., 11, 1289-1300 (2000).
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