Experiments on submerged pitching plate under water waves

A submerged pitching plate was suggested as an active wave Control device by Yip and Chwang (1996, 1997) (Figure 1). Based on the linear wave theory, they determined the plate performance in terms of reflection and transmission coefficients versus other physical parameters of wave, plate, porosity and pitching. The experimental investigation on a pitching plate is conducted to compare the theoretical analysis with the laboratory results in order to verify the linear theory and to determine its application range, especially for the variation of pitching and porosity. To meet the theoretical conditions, experimental tests are carried out in a wave flume with a reflection-absorbing wavemaker. The pitching plate is submerged in water while its submergence depth, pitching amplitude and phase are adjustable. Two pairs of wave gauges are placed in front of and behind the plate and used to determine the reflection and transmission coefficients by employing the Goda and Suzuki (1976) method. Under various combinations of steady conditions, the overall agreement between experimental and theoretical results is satisfactory. Discrepancy occurs only when the wavelength is relatively short or the depth of submergence is shallow.