Simultaneous flow-field measurements of velocity and passive-scalar mixture-fraction from a point-source in a turbulent boundary layer

High resolution simultaneous Particle Image Velocimetry (PIV) and Planar Laser-induced Fluorescence (PLIF) are conducted to study transport and mixing of a passive scalar within the boundary layer. This was performed by an acetone-air mixture injected isokinetically at h/δ~0.2 to compare with previous point-measurements. The field-of-view was approximately 2δ x 1.4δ which encompassed the entire boundary layer height and the injection point of the scalar. This setup captured the initial advection and mixing of the stream within the boundary layer. Post-processing of the data generated quantitative high spatial resolution velocity and scalar fields in the aforementioned plane. From these measurements, single- and two-point correlations are computed from the velocity and scalar fields, as well as cross-correlation between the two fields. These values are compared to data provided by single point measurements in the literature. The multipoint statistics conducted in this experiment provide a comprehensive picture of the coupled structure of velocity and scalar fields, and of the scalar transport by the turbulent scales.