REFLECTION OF IRREGULAR WAVES AT PARTIALLY REFLECTING STRUCTURES INCLUDING OBLIQUE WAVE APPROACH

Hans-Joachim Scheffer, Soren Kohlhase

Abstract


The reflection of irregular seas is increasingly considered in coastal engineering and harbour design as well with respect to wave pattern at the structure and energy dissipation as regarding the dimensioning of structures exposed to waves. It becomes evident that the three-dimensional sea state (oblique wave approach, irregularity of the waves) at partially-reflecting structures of a complex design cannot be described by means of a constant reflection coefficient alone, as is common practice. This is due to the fact that the coefficient is largely frequency-dependent and the physically effective reflection point of the structure cannot be clearly specified. In the light of this, basic investigations on wave reflection have been performed with different partially-reflecting structures, wave spectra and wave approach angles. In addition to laboratory experiments using both a wave flume and a wave basin, a theoretical solution based on diffraction theory was determined to describe the wave field in the reflection area of various structures. The investigations were restricted to non-breaking wave conditions. The reflection behaviour of structures is expressed by a complex reflection coefficient, containing two parameters, which have to be determined by model tests.

Keywords


reflection; irregular waves; partially reflecting structures; oblique waves

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