Time dependent investigation of the wave induced scour at the trunk section of a rubble mound breakwater

Abstract

Rubble-mound breakwaters are the most commonly constructed marine structures for various port structures with different areas of usage. Local scour around these structures, which leads to stability losses or even failure, has great importance for the design of these structures both economical and safety perspectives. Within the scope of this paper, wave-induced local scour at the toe of rubble mound breakwaters placed on an erodible seabed was studied both experimentally and numerically. Experiments were carried out on the wave channel in Hydraulics Laboratory of Dokuz Eylul University. Time dependent scour depth and wave characteristics were observed with ultrasonic methods. An equivalent numerical wave channel was used to compare and observe scour mechanism. Regular waves were generated by using Flow3D, one of the advanced computational fluid dynamics (CFD) software. Scour patterns were investigated for relatively coarse and fine seabed material with 1.85 mm and 0.55 mm grain median diameters under various wave scenarios with a breakwater slope of 1:1.5 and 1:1.75 which are widely used in construction. From the experimental and numerical findings obtained from the study, it is understood that the numerical model was found to be compatible with experiments.