Method for Determining the Sea Waves Curvature Using Wave Buoys Conventional Shape

• Main Author: K. A. Gleb
• Format: Article
• Language: Russian
• Published: Saint Petersburg Electrotechnical University "LETI" 2020-10-01
• Series: Известия высших учебных заведений России: Радиоэлектроника
• Subjects: wave buoy; directional spectrum; wave curvature; wave speed; numerical differentiation; fourier transform
• Online Access: https://re.eltech.ru/jour/article/view/454

Introduction. Modern wave buoys due to their design make it possible to determine a directional wave spectrum using five coefficients of the Fourier series. However, up to nine members of the series can be determined from wave surface measurements. To determine the missing four members, information about wave curvature is necessary. It cannot be obtained by direct measurements with wave buoys of a conventional shape - a sphere, a cylinder or a saucer. The lack of information about the curvature of waves when determining the directional spectrum leads to its low resolution and to the presence of negative regions.Aim. To develop a method for determining the curvature of waves from measurements with conventional shape wave buoys.Materials and methods. Theoretical substantiations of the proposed method were presented, as well as mathematical modeling of irregular wave processes in a wide range of wave intensities and an experimental study of three wave spectra with a threefold repetition of each of them.Results. Numerical simulations demonstrated a good agreement between the calculated curvature and the set values. The variance deviation was less than 1%. The experimental study demonstrated a greater deviation in variance - up to 9%, which can be explained by the influence of an instrumental error and by an unaccounted influence of reflected waves.Conclusion. On the basis of the study, the method for determining the curvature of waves by numerical differentiation of wave slope measurements using information on a wave propagation speed has been developed. The method was supplemented by correcting amplitude values according to the criterion of matching the spectral characteristics of wave processes. Additional studies of the developed method are required to determine the influence of wave factors such as wave steepness, spectrum width, random multidirectional waves, etc. on the calculated curvature and on the directional spectrum.