Laboratory Tests on the Reflection Coefficient of a Perforated Caisson

Leopoldo Franco, Claudia Cecioni, Giorgio Bellotti, Thomas Lykke Andersen

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This paper presents new tests on a perforated vertical wall caisson. The tests aim at evaluating the reduction of the reflection coefficient caused by different perforations. The reflection coefficient is estimated using the novel nonlinear methods proposed by Lykke Andersen et al. (2017) and Eldrup and Lykke Andersen (2019). The structure under investigation is, at prototype scale, 21.50 m high, 35.55 m long and 13.90 m wide, divided into 3 rows of 8 cells. The caisson has a recurved ‘nose’ and air vents on the parapet wall. An identical plain wall caisson without absorbing chambers is also tested for comparison. Two-dimensional laboratory tests have been carried out at Department of Engineering of Roma Tre University with both irregular and regular waves, reproducing mild wave conditions and design wave conditions. Two water levels have been used, reproducing the mean water level and a set-up condition of +0.5 m. Four structural layouts are tested in order to study various perforation types. Furthermore, the effect of the wave obliquity and of the short crestedness on the reflection coefficient is discussed using some 3D laboratory data obtained back in the 1995 but not published before.
Original languageEnglish
Title of host publicationThe 8th International Coastal Structures Conference 2019
EditorsNils Goseberg, Torsten Schlurmann
Place of PublicationKarlsruhe
PublisherBundesanstalt für Wasserbau
Publication date2019
ISBN (Electronic)978-3-939230-64-9
Publication statusPublished - 2019
EventCoastal Structures Conference 2019 - Coastal Research Center (Forschungszentrum Küste, FZK), Hannover, Germany
Duration: 30 Sept 20192 Oct 2019
Conference number: 8


ConferenceCoastal Structures Conference 2019
LocationCoastal Research Center (Forschungszentrum Küste, FZK)


  • Perforated caisson
  • Wave reflection
  • Hydraulic model
  • Vertical breakwaters
  • Wave flume
  • Wave generation
  • Active wave absorption


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