Transmission Performance of Submerged Semicircular Breakwaters for Different Radii and Submergence Ratios

Abstract

The paper presents the results of a series of laboratory experiments that were conducted in a 2D monochromatic wave flume of the department to evaluate the transmission characteristics of scaled down semicircular breakwater (SBW) physical models of different radii (R) for different submergence ratios (d/h c ), where d is the depth of water and h c is the height of the breakwater crest from the sea bed. The radii of the breakwater models studied were 20 cm, 22.5 cm, 25 cm, and 27.5 cm and d/h c values used varied from 1.067 to 1.667. The wave climate along the Mangalore coast of India was used for arriving at the various wave parameters. Incident wave heights (H i ) used varied from 3 to 18 cm, wave periods (T) ranged from 1.2 s to 2.2 s with water depths (d) of 40 cm, 45 cm and 50 cm. The data collected was analyzed by plotting the non-dimensional graphs depicting the variation of transmission coefficient K t (K t = H t /H i , where H t = transmitted wave height) with wave steepness H i /gT 2 for different R/H i and d/h c values. It was found that transmission coefficient decreased as the incident wave steepness increased for different submergence ratios. Also as d/h c increased, it was found that K t increased initially and then decreased.