Experimental study on scour around a pile in multidirectional (Spreading) random waves

authored by

Alexander Schendel, Arndt Hildebrandt, Torsten Schlurmann

Abstract

The progressive expansion of offshore wind energy towards greater water depths demands for an optimization of foundation structure designs to a wider range of load conditions. In offshore waters, wind driven wave irregularity and directionality become important aspects of realistic sea states. To further improve the scour prediction in marine environment a novel experimental study was conducted to investigate the influence of multidirectional waves on the scouring process. The tests were carried out in the 3D wave basin of the Ludwig-Franzius-Institute, Leibniz University Hannover, Germany and a monopile structure was simulated by a transparent pile made of acrylic glass. The test program included experiments with multidirectional waves as well as superimposed with oblique currents and were complemented by tests with unidirectional waves to provide additional reference for comparison. Despite identical total wave energy between the multi-and unidirectional wave spectra, distinct differences in scour depth and rate could be observed, which inevitably can only be attributed to the influence of wave spreading on morphodynamical processes around the pile. For wave-only conditions scour depths induced by multidirectional waves were on average 33% smaller than those for unidirectional waves. In combined wave and current conditions scour depths were found to slightly larger for multidirectional than for unidirectional waves.

Organisation(s)

Ludwig-Franzius-Institute of Hydraulics, Estuarine and Coastal Engineering

Type

Conference contribution

Pages

267-273

No. of pages

7

Publication date

12.2019

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Water Science and Technology, Ocean Engineering, Environmental Engineering

Sustainable Development Goals

SDG 14 - Life Below Water