Offshore Technology Research Center

 

OTRC Project Summary

Project Title:

Generation and Analysis of Multi-Directional Waves

Prinicipal Investigators:

John Niedzwecki

Sponsor:

National Science Foundation

Completion Date:

October 1999

Final Report ID#

A102(Click to view final report abstract)

In the present research, we will try to provide a better understanding of the generations and analysis of three-dimensional wave fields.  To achieve this a test matrix, which included oblique regular waves, regular waves, bi-directional waves multi-directional waves and focused waves (bull’s eye waves) was followed.  The design of tests includes the choice of the wave parameters and in certain cases, it has been necessary to have input-files for the GEDAP program that computes the drive signals of the wave-maker.  The input file is the wave elevation variance table corresponding to the wave field’s spectral density.  A series of Matlab programs was created to that purpose.  To make detailed laboratory measurements, the construction of appropriate arrays of wave elevation recorders was needed.  Their location in the waved basin depended on the waves to be tested; the configuration of the probes for the measurements, the construction of appropriate arrays of wave elevation recorders was needed.  Their location in the wave basin depended on the waves to be tested; the configuration of the probes for the measurement of multi-directional waves is similar to the CERC array used by Panicker and Borgman (1970).

For bull’s eye waves (Lamb, 1932), a four-gage configuration was used.  Comparison of the resolution of the four five wave gages configurations was made.  The analysis of these waves required a particular array design in order to determine: 

  • Amplitude of the wave in the converging field,
  • Interaction at the point of convergence,
  • Transverse profile and maximum wave height,
  • Characteristics of the diverging field after the point of convergence.

Dr. Borgman’s program NUPSEC was implemented for the processing of the multi-directional waves data using the MEM.  Although no improvement to the method were sought, the implementation of another means for the analysis of measured data, allowed one to gain confidence in the analysis method.  In addition to the comparison of some results, it allowed on to point out and study the problems encountered during the generation and analysis of multi-directional waves.

 

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