Generation of short waves in a towing tank

Abstract

Experiments are reported, which were conducted at the University of Newcastle upon Tyne to generate short regular waves having lengths in the range up to 2 ft (0.61 m), to be subsequently used in wave-excited two-node resonant vertical vibration (springing) model tests. A small, simple, vertically oscillating wedge shaped wavemaker was designed and built for this purpose.

Wave heights are plotted against wavelength for various values of wavemaker osciallation amplitude and amplitude ratios against the non-dimensional frequency parameter ${\mathit{\omega }}^2$ Bn/2g. These results behave according to expectations. The propagation characteristics of the waves down the length of the tank are examined and the wave height attenuation is found to be considerably larger than that predicted by theory.

The generated waves can be used with confidence in the vibration model tests and recommendations for future work include theoretical derivation of the amplitude ratios and examination of the theoretical methods for estimating viscous waveheight attenuation.