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Gaussian wave packets — a new approach to seakeeping testsof ocean structures

Clauss, Günther F. / Bergmann, Jan

The transient wave train techniques has been widely used in testing ocean structures. The methodpresented here is based on a special Gauss-modulated amplitude spectrum. These wave groups of limited length can be superimposed, the actual surface elevation being a function of packet characteristics and initial time lag.The application of this technique is demonstrated in three cases presenting a semisubmersible,an articulated tower and a floating oil skimmer. It is shown, that a particular problem needs a tailored wave packet containing sufficient energy all over the relevant frequency range. These packets are designed by superimposing individual Gaussian wave groups.The new seakeeping test techniques has the following advantagesu- The wave train is well defined at any location of the tank.- The wave elevation and spectrum can be standardised or easily adapted to any specific problem.- The duration of the test is very short; reflections (beach) do not interfere the results. At theculmination point the length of the wave train is small. This facilitates short duration seakeeping and manoeuvring tests.- The results show high resolution and are in good agreement with regular wave test data.Summarising, the Gaussian wave packet method is a versatile technique yielding precise and highly resoluted results in a short time.