Perforated-ball velocity meter measurements of the water wave kinematics in nonlinear, long and short crested waves

Direct measurement of the wave kinematics in laboratory and field has alway s occupied a central place in experimental research in water waves. In this paper, a laboratory scale, multi-stage three component Perforated-ball Vel ocity Meter (PVM) has been used to measure the wave kinematics in linear as well as nonlinear waves, in long crested as well as short crested random w aves. Special attention is devoted to measurement of the near surface kinem atics, especially in regular nonlinear waves. The laboratory measurements i n deep and shallow water wave flumes and wave basin have been conducted usi ng the PVM and the measured kinematics have been compared with the calculat ed kinematics based on several semi-empirical methods as well as ultrasonic current meter measurements. The comparisons have been found to be excellen t at all water depths. (C) 2001 Elsevier Science Ltd. All rights reserved.