An optic-based method that utilizes the particle-laden images captured during high-speed particle image velocimetry (HSPIV) measurements is presented, aiming to explore the probabilistic mean characteristics of the free surface profiles and velocity fields of a free jet with high-frequency random fluctuations over a chute. The technique based on the gray-level gradients in the smoothed gray level distribution of the contrast-enhanced images is used to determine the probabilistic mean features of the free jet, right beneath and above which the water-air interfaces have I%/(100  I)% intermittent appearance of air/water phase and (100  I)%/I% fitful show-up of water/air phase. Further, the cross-correlation calculation for HSPIV measurements is employed to obtain the instantaneous and probabilistic mean velocity fields of the free jet. A target experiment of the free jet having a mean water-depth of 2.76 cm and a Froude number of 3.92 over a 17 chute model is performed in a re-circulating water channel to demonstrate the application of this method.

Included in

Engineering Commons