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Experiments by Invited Researchers

 

Effect of very oblique waves on wave run-up and wave overtopping (CornerDike)

Project acronym: HyIV-DHI-05
Name of Group Leader: Reinhard Pohl, Prof. Dr.-Ing. habil.
User-Project Title: Effect of very oblique waves on wave run-up and wave overtopping (CornerDike)
Facility: Shallow water basin
Proceedings TA Project: WAVE RUN-UP AND WAVE OVERTOPPING UNDER VERY OBLIQUE WAVE ATTACK (CORNERDIKE-PROJECT)
Data Management Report: Report

User-Project Objectives

Many dikes in coastal areas, estuaries or harbours have angles between the levee axis and the incoming wave direction of more than 45°. Since only very few experiments are available for angles over 45° and the available formulas show considerable differences for angles of wave attack over 45°, experimental data are required to estimate the wave run-up and wave overtopping behaviour in these cases and to reduce the remaining uncertainties. Knowledge on wave run-up and wave overtopping for very oblique wave approach is required for a better design of flood protection structures along rivers, estuaries and coasts such as dikes. The consideration of this effect will result in a more reliable design of dikes and levees. The experiments will be performed for a 1:4 slope typical for river, estuarine and coastal dikes. The dike will be divided into two separate parts. One part (P) will be constructed parallel to the wave generator to run reference tests (e.g. comparison of the data to the HydralabIII-FlowDike-project) and the other part of the dike (N) will be constructed normal to the wave generator to investigate the effect of very oblique wave attack. The test programme covers model tests on wave run-up and wave overtopping for different wave conditions, different current velocities (parallel to dike (P)) and angles of wave attack between -45° and 45° with respect to the wave generator. Therefore, angles of wave attack between 45° and 135° will be investigated with respect to the dike (N).

Short description of the work carried out

The analysis of the comprehensive test data is going on. The final report is being prepared and is expected to be published in early 2014.

Highlights of important research results

Analyses of model tests on a 1:4 sloped sea dike with a 90° corner give information on the influence of very oblique waves on wave overtopping. Following statements can be made on the basis of a first analysis: • Overtopping units which are located next to the corner of the dike show higher overtopping discharges for angles of wave attack between 7.5° and 30° than for perpendicular wave attack. An influence of the corner section is assumed. • Increasing angles of wave attack (greater than 45°) lead in general to decreasing overtopping rates for multidirectional sea states with spreading 34°. Wave overtopping occurred even during tests with multidirectional waves and attack angles greater than 100°. • The behavior of waves and wave overtopping along the dike arms depends on the directional spreading of the tested sea states and the applied wave directions. Consequently the ratios of measured overtopping discharges at several positions along the dike depend on these parameters and differ for long crested and short crested waves. Further analysis is required with reference to former investigations and consideration of incident wave parameters.

Publications
Bornschein A.; Pohl R.; Wolf V.; Schüttrumpf H.; Scheres B.; Troch P.; Riha J.; van der Meer J.; Spano M. WAVE RUN-UP AND WAVE OVERTOPPING UNDER VERY OBLIQUE WAVE ATTACK (CORNERDIKE-PROJECT) , 2014

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