PARTICLE IMAGE VELOCIMETRY FOR PREDICTIONS OF ACCELERATION FIELDS ANDFORCE WITHIN FLUID-FLOWS

We describe an experimental investigation of various methods of using the non-intrusive particle image velocimetry (PIV) technology to obtai n the acceleration field of fluid flows and particularly the force bei ng exchanged between a fluid flow and its boundaries. Methods based on the Lagrangian and the Eulerian specifications respectively have been developed, applied to experiments and compared. The experiments were performed by using a four-CCD-camera system designed to acquire betwee n two and lour frames in a fast time sequence, to provide single- or m ultiple-exposure PIV images of general fluid flows, The experiments in volved various types of surface waves impinging upon a vertical wall a t the end of a flume. Simultaneous monitoring with various transducers provided the experimental evaluation of the force predictions, wherea s numerical simulations and PIV measurements have been used to validat e the techniques for determining accelerations.