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Investigation of Bound and Free Surface Waves in Microwave and Acoustic Wind-Wave Tank Systems

Khalid S. Jameel --- Genady Ibeshiyv --- Latia K. Parshieva --- Patrick J. Vodesko

Iraqi Journal of Applied Physics المجلة العراقية للفيزياء التطبيقية
ISSN: 18132065 23091673 Year: 2018 Volume: 14 Issue: 2 Pages: 11-18
Publisher: iraqi society for alternative and renewable energy sources and techniques الجمعية العراقية لمصادر وتقنيات الطاقة البديلة والمستجدة

Abstract

Microwave and acoustic systems operated in the large wind-wave tank show that most small-scale waves produced at large angles to the wind are products of breaking events bound to longer waves in the tank. These longer waves propagate at the dominant wave phase speed for fetches near 7m but travel at speeds corresponding to the phase speed of a wave half as long as the dominant wave at fetches near 26m. The microwave and acoustic systems operated at both 8mm and 2cm wavelengths. Measurements were made at seven wind speeds, five incidence angles, seven azimuth angles, and two nominal fetches. Two peaks were found in either the microwave or acoustic Doppler spectrum when looking upwind or downwind, but never in both. The sum of these spectral densities, the total short wave spectral density, was similar to, but lower than, previous measurements. The nature of millimeter-length bound waves was found to be different at long fetch than at short fetches, a feature not observed in centimeter-length bound waves.

Keywords

Wind waves --- Bound surface wave --- Free surface wave --- Acoustics