Summary
The objective of this project was to develop a functioning laboratory instrument that utilizes image processing techniques, in conjunction with real-time video images of wave surfaces, to provide an accurate measure of surface particle displacements in the horizontal direction. These particle displacements were then used to calculate the horizontal velocity component of the waves surface kinematics. The instrument hardware consists of a personal computer for image and data analysis, a frame grabber board for digitizing the video images and importing these images into the computer, and a video cam-corder for filming the particle/wave interactions. The software used for image enhancement, image analysis and particle tracking is part of the research effort and was created by the instrument developer.
Once the instrument is developed, it will be used to measure surface kinematics in a series of regular and irregular waves. The results from the regular wave experiments will be compared to high-order nonlinear wave theory (Cokelet, 1977) while the irregular wave results will be compared to the Hybrid Wave Model (Zhang et at, 1992) as well as to commonly used “stretching” and “ extrapolation” methods.
Comparison of the video instrument’s results to those obtained by the numerical models will not only validate the video measurement technique, but also the surface velocity predictions of the numerical models. In addition, the validation of the video measurement results will aid in the feasibility study of expanding this instrument from 2–dimensional to 3-dimensional measurement capabilities.
