טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentShani-Zerbib Almog
SubjectNew Laser Slope Gauge Design for Laboratory Scale
Wind-Wave Measurements
DepartmentDepartment of Civil and Environmental Engineering
Supervisor Dr. Dan Liberzon
Full Thesis textFull thesis text - English Version


Abstract

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The problem of wind-waves has been in the focus of scientific research for decades. Although very simple at the first glance, the exact nature of mechanisms governing wave growth by momentum and energy transfer between turbulent atmospheric boundary layer and water waves is still largely not understood. The scientific research of this topic is complex and often requires staging sophisticated experiments. The later rely on our ability to produce accurate measurements of various parameters of both wind flow and wave fields. However, our mere ability to obtain reliable representation of the wave energy directional distribution is severely limited by the currently available instrumentation and the exiting methods of data processing.

Due to the complicated non-linear interactions governing the wave field, causing it usually to have a broad spectrum of wave components of various wavelengths and frequencies and propagating on a two-dimensional water surface, a statistical approach was hence adopted to describe such wave fields using spectral analysis of the surface elevation fluctuations. Spectral analysis is needed in order to successfully measure and analyze a wave field. Whereas obtaining one dimensional frequency or wavenumber spectrum is relatively simple and requires only the knowledge of surface elevation fluctuations time series, determination of the directional waves spectrum in terms of wave energy density distribution as a function of frequency and direction is a much more complicated task.

Here lies the need for a new laser slope design aimed to produce directional data that will help acquire more accurate two-dimensional energy density spectra. The prototype presented here is planned to be of use in laboratory scale wind-wave measurements and therefore has to be small in size, simple to operate, accurate, reliable and low priced.

In the work presented here the prototype is introduced and its design is elaborated, accompanied by series of tests staged to examine the prototype functionality.