Banner - Hydraulic Research and Testing Facility
Research Opportunities
Efficient Algorithms for the Mechanical Generation of Waves
Brian Giesbrecht, 1996

The laboratory setting provides an opportunity to elucidate various aspects of wave related phenomena. However, the mechanical generation of waves by an impervious wave board results in a number of second-order problems not inherent with wind-generated waves.

Since second-order processes play a fundamental role in many wave-related phenomena, the accurate reproduction of "natural" wave conditions is central to meaningful laboratory experiments. Mathematical algorithms exist that eliminate the spurious second-order waves caused by a first-order control signal. These mathematical algorithms were encoded into an interactive software package using MATLAB to create a first-order wave train and correct it for second-order effects based on user-defined inputs.

The efficiency of the algorithms was enhanced using a proposed method of thresholding that limits the range of frequencies over which the various corrections are applied. The software package (WAVGEN) was tested in the HRTF random wave flume. The bispectrum was used to examine the ability of the second-order algorithms to eliminate spurious waves. Bichromatic wave trains showed clearly that the algorithms reduced the second-order wave effects. Random wave tests showed similar results albeit less clearly given the broad-banded nature of the random wave spectra.

| Return to Research |