Quantification of Mixing and Mixing Rate from Experimental Observations

Experimental datasets from a variety of mixing flows are analyzed to assess the degree of mixing and the rate of mixing. The concentration field of an axisymmetric jet is measured at ten downstream locations by optical imaging of Rayleigh scattering from a laser sheet. A new measure of mixedness, based on entropy considerations, and a related mixing rate is calculated for each of the locations. In agreement with theory, the mixedness of the self-similar jet is constant along the length of the jet. The measures allow us to locate the instantaneous realization that is the most typical in terms of mixedness and mixing rate. Also analyzed is the mixing of a row jets injecting fluid into a crossflow. The jets are sufficiently close that there is significant interaction between neighboring jets. The mixedness and mixing rate were calculated. Well mixed regions have a low mixing rate, while poorly mixed regions tend to mix most rapidly. The mixedness and mixing rate allow the assessment of th...