Transmission performance of submerged semicircular breakwaters for different radii and submergence ratios

摘要

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.