Simultaneous concentration and velocity measurements using combined laser-induced fluorescence and laser Doppler velocimetry : Application to turbulent transport

This paper describes the implementation of an optical technique, allowing to perform concentration and velocity measurements simultaneously and at the same point. This method is based on the coupling of laser-induced fluorescence of rhodamine B, applied to the determination of local concentration, and laser Doppler velocimetry. The method developed provides an accurate measurement of the concentration-velocity cross-correlation. The latter is a parameter linked to the eddy diffusivity tensor of a passive contaminant. This method was tested with a turbulent submerged free jet and it allowed the determination of the mean field of concentration and velocity, the concentration-velocity cross-correlation, and the local eddy diffusivity. (Author)