AbstractIn the present paper we examine the performance of two very common types of wave absorbing porous marine structures under regular oblique waves. The first structure consists of a single perforated vertical seawall, whereas the second consists of two perforated vertical seawalls creating what is called a chamber system (Jarlan type breakwater). The structures are surface piercing thus eliminating wave overtopping. Two methods are used for the present investigation. In the first method the problem of the interaction of obliquely incident linear waves upon a pair of porous vertical seawalls is first formulated in the context of the linear diffraction theory. The resulting boundary integral equation, which is matched with far-field solutions represented in terms of analytical series with unknown coefficients, and appropriate boundary conditions at the free surface, seabed and seawalls, is then solved numerically using the multi-domain boundary element method. In the second method a semi-analytical solution is developed by means of the eigenfunction expansions and a minimization approach using a least square method. In both methods the dissipation of the wave energy due to the presence of the perforated seawalls is represented by a simple yet effective relation in terms of the porosity parameter appropriate for thin perforated walls. The results are presented in terms of reflection and transmission coefficients, and the wave energy dissipation. Effects of the incident wave angles, porosities and depths of the walls and other major parameters of interest are explored.
Das, P., Dolai, D., and Mandal, B., 1997. Oblique wave diffraction by parallel thin vertical barriers with gaps. Journal of Waterway, Port, Coastal, and Ocean Engineering, ASCE, 123(4), 163-171.
Huang, Z., Li, Y., and Liu, Y., 2011. Hydraulic performance and wave loadings of perforated/slotted coastal structures: A review. Ocean Engineering, 38, 1031-1053.
Koley, S., Behera, H., and Sahoo, T., 2015a. Oblique wave trapping by porous structures near a Wall. Journal of Engineering Mechanics, ASCE, 141 (3).
Koley, S., Sarkar, A., and Sahoo, T., 2015b. Interaction of gravity waves with bottom-standing submerged structures having perforated outer-layer placed on a sloping bed. Applied Ocean Research, 52, 245-260.
Li, Y., Liu, Y., and Teng, B., 2006. Porous effect parameter of thin permeable plates. Coastal Engineering Journal, 48(4), 309-336.
Liu, Y., and Li, Y., 2011. The interaction of oblique waves with a partially immersed wave absorbing breakwater. Proceedings of 32nd International Conference on Coastal Engineering, ASCE, 32(1).
Liu, Y., Yao, Z. and Li, H., 2015. Analytical and experimental studies on hydrodynamic performance of semi-immersed Jarlan-type perforated breakwaters. China Ocean Engineering, 29(6), 793-806.
Porter, R., 1995. Complementary methods and bounds in linear water waves. Doctoral thesis, University of Bristol, UK.
Yu, X., 1995. Diffraction of water waves by porous breakwaters. Journal of Waterway, Port, Coastal, and Ocean Engineering, ASCE, 121(6), 275-282.