Faculty Publications
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Item Laboratory investigation on hydraulic performance of enlarged pile head breakwater(Elsevier Ltd, 2020) Suvarna, P.S.; Hunasanahally Sathyanarayana, A.H.; Umesh, P.; Shirlal, K.G.Coastal erosion of beaches has been a common problem around the world. One of the eco-friendly control measures for coastal erosion is to dissipate the energy of waves impinging on the shores by constructing offshore breakwater. Pile breakwater is one such type of offshore breakwater that consists of a number of closely spaced piles. Construction of piles at closer spacing is highly challenging and expensive. This problem can be addressed by reducing the number of piles and modifying the pile with an enlarged head in the vicinity of the water surface, where wave energy is concentrated. In the present study, an experimental investigation on the hydraulic performance of enlarged pile head breakwater is conducted in a wave flume. The concept breakwater is subjected to monochromatic waves of varying wave heights, wave periods and water depth. The experimental results show that the least value of transmission coefficient is 0.62 and reflection coefficient is 0.123 with the highest value of dissipation coefficient of 0.77 for the structural configuration of b/D ratio of 0.2, D/Hmax of 0.6 and Y/Hmax of 1.0 at a water depth of 0.3 m. Observed results are encouraging and are in line with the similar type of pile breakwaters in a single row. The present experimental data is also validated with the available theoretical solutions. Since the results from the compared theoretical solution are not in good agreement, a hybrid theoretical model is reconstructed based on experimental results of pile head breakwater. The proposed modified version of the hybrid equation predicts encouragingly better transmission, reflection and dissipation coefficient than the existing solutions. Moreover, the results predicted by the proposed hybrid equation are in good agreement with that of other similar pile breakwater models. © 2020 Elsevier LtdItem Hydraulic performance of perforated enlarged pile head breakwaters through laboratory investigation(Elsevier Ltd, 2021) Suvarna, P.S.; Hunasanahally Sathyanarayana, A.H.; Umesh, P.; Shirlal, K.G.An economical, ecofriendly and efficient breakwater system is vital for coastal protection and harbour tranquility. In this regard, various researchers are working to develop the appropriate solutions to encounter site-specific challenges. With this viewpoint, concept of enlarged pile head breakwater is developed. The study focuses on improving the hydraulic efficiency of pile breakwater by enlarging the structure near the free surface and providing it with perforations. Effect of percentage distribution of perforations, size of perforations and percentage of perforations on wave transmission, reflection and dissipation characteristics of the structure is investigated. The physical experiments are conducted in a two-dimensional wave flume under varying monochromatic wave climates. Results indicate that the pore size highly dominants the wave attenuation than considering the increasing percentage of perforations with the small size of the pore. Perforations effectively reduce the Kt of about 10%–18% to that of non-perforated pile head breakwater. Hydraulic efficiency of enlarged pile head breakwater is optimum when D/Hmax = 0.6, Y/Hmax = 1.0, b/D = 0.2, S = 0.25D, pa = 75% and P = 22.5 at 0.3 m water depth. A hybrid theoretical solution is developed based on the current set of experimental data for the quick estimate of hydraulic coefficients. The proposed hybrid equation for the perforated pile breakwater predicts more desirable values of Kt, Kr and Kd. The proposed concept of breakwater gives a reasonably enhanced hydraulic efficiency than the compared type of breakwaters. © 2021 Elsevier Ltd