Determination of the velocity-concentration correlations by digital image processing

Visualization and image processing have been widely used during this last decade for the measurements of velocity and concentration fields in fluid flows. A first step of the method consists in recording single or multi-exposed flows seeded by solid particles or fluorescent species. In a second step, the physical informations from these photographs are obtained. The advantage of these techniques is that the quantities are measured over an entire plane of the flow field so that the accuracy and spatial resolution mainly depend on the optical set up. From these data, instantaneous velocity and concentration fields can easily be obtained.