Faculty Publications

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Now showing 1 - 7 of 7
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    Hydraulic performance of tandem breakwater with concrete cubes as armour units
    (2009) Rao, M.; Shirlal, K.G.; Rao, S.; Bharadwaj, P.
    Tandem breakwater system consists of a conventional breakwater protected by a seaward submerged reef. The paper discusses physical model study on the hydraulic performance of an isolated as well as tandem breakwater system subjected to varying wave climate and water depths, while keeping a constant crest width of submerged reef. The breakwater in both the cases are armoured with concrete cubes and the submerged reef is constructed with natural stones. It is found that the isolated breakwater is damaged for all waves except those of period 2.5 s. While a submerged reef of crest width (B) 0.40m placed at a seaward spacing(X) of 2.5m transmits only 52% to 81% of the incident wave height and thereby reduces the wave force on the main structure which inturn protects the inner main breakwater completely without causing any damage.
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    Effect of water depth on wave reflection and loss characteristics of an emerged perforated quarter circle breakwater
    (CESER Publications Post Box No. 113 Roorkee 247667, 2016) Shahulhameed, S.; Hegde, A.V.; Rao, S.
    Quarter circle breakwater is a new-type breakwater first proposed by Xie et al. (2006) on the basis of semicircular breakwater. Quarter circle breakwater is usually placed on rubble mound foundation and its superstructure consists of a precast reinforced concrete quarter circular surface facing incident waves, a horizontal bottom slab and a rear vertical wall. A series of experiments were conducted in a two dimensional monochromatic wave flume on a seaside perforated quarter circle breakwater model. The present study investigates the wave reflection and loss characteristics on an emerged seaside perforated quarter circle breakwater of three different radii and with ratio of spacing to diameter of perforations equal to 5, for different water depths and wave conditions. The results were plotted as non-dimensional graphs and it was observed that the reflection coefficient increases with increase in wave steepness and increase in ratio of height of breakwater structure to water depth. It was also found that the loss coefficient decreases with increase in wave steepness and increase in ratio of height of breakwater structure to water depth. © 2016 IJED.
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    Wave Reflection and Loss Characteristics of an Emerged Quarter Circle Breakwater with Varying Seaside Perforations
    (Springer India sanjiv.goswami@springer.co.in, 2017) Shahulhameed, S.; Rao, S.; Hegde, A.V.
    Breakwaters are one of the most important harbour structures constructed to withstand and dissipate the dynamic energy due to the action of the waves. Due to fast growing need of the universe and advances in technology different types of breakwaters are being developed. Quarter circle breakwater is a new type of breakwater emerged from semi circular breakwater and the first model was developed in Peoples Republic of China (2006). Quarter circle breakwater with perforations posses merits of caisson as well as perforated breakwaters such as low weight, requires less materials, suited for poor soil conditions, easily transported, handled and placed at the site, aesthetically pleasing, cost effective, eco-friendly and stable. Therefore it is necessary to carry out detailed studies on hydrodynamic characteristics to investigate the suitability and applicability of various types of quarter circle breakwaters. The present study investigates the wave reflection and loss characteristics of an emerged seaside perforated quarter circle breakwater of radius 55 cm and with varying ratios of spacing to diameter of perforations, for different water depths and wave conditions. The tests were conducted in the two-dimensional monochromatic wave flume available in Marine Structures laboratory of Department of Applied Mechanics and Hydraulics of National Institute of Technology, Surathkal, Karnataka, India. The results were plotted as non-dimensional graphs and it was observed that the reflection coefficient increases with increase in wave steepness for all values of ratio of height of breakwater structure to water depth. For a constant water depth, wave reflection increases with increase in ratio of spacing to diameter of perforations. It was also found that the loss coefficient decreases with increase in wave steepness for all values of ratio of height of breakwater structure to water depth, and ratio of spacing to diameter of perforations. © 2017, The Institution of Engineers (India).
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    Multiple Nonlinear Regression Analysis for the Stability of Non-overtopping Perforated Quarter Circle Breakwater
    (Editorial Board of Journal of Harbin Engineering, 2020) Shahulhameed, S.; Rao, S.; Hegde, A.V.
    Breakwaters have been built throughout the centuries for the coastal protection and the port development, but changes occurred in their layout and criteria used for the design. Quarter circle breakwater (QBW) is a new type evolved having advantages of both caisson type and perforated type breakwaters. The present study extracts the effect of change in the percentage of perforations on the stable conditions of seaside perforated QBW by using various physical models. The results were graphically analyzed using dimensionless parameters and it was concluded that there is a reduction in dimensionless stability parameter with an increase in steepness of the wave and change in water depth to the height of breakwater structure. Multiple non–linear regression analysis was done and the equation for the best fit curve with a higher regression coefficient was obtained by using Excel statistical software—XLSTAT. © 2020, Harbin Engineering University and Springer-Verlag GmbH Germany, part of Springer Nature.
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    Oblique wave propagation through composite permeable porous structures
    (Springer Science and Business Media Deutschland GmbH, 2023) Krishna, K.R.A.; Karaseeri, A.G.; Karmakar, D.
    In the present study, the porous breakwater system consisting of a porous block and a permeable barrier is analysed to understand the wave dissipation due to the composite porous structure. The linearised wave theory is adopted to analyse the wave interaction with three different configurations of the composite structures including (a) porous structure and fully extended vertical barrier, (b) porous structure and bottom-standing barrier and (c) porous structure and surface-piercing barrier. The eigenfunction expansion method along with orthogonal mode-coupling relation is adopted to determine the wave reflection and transmission characteristics along with wave force on the porous structure and barrier, and surface deflection in incident and transmitted region. The experimental investigation is performed for the composite breakwater system and the results obtained are compared and validated with the numerical results. The composite breakwater system is studied for various parameters such as relative water depth, porosity of structure and barrier, structural thickness to wavelength ratio, water depth to wavelength ratio and gap between the structure and barrier. Further, the comparative study is performed with the results available in the literatures. The proposed study exhibits an informative result for the wave energy attenuation by the composite breakwater system which can be designed and implemented in coastal and harbour regions for achieving the tranquillity. © 2022, The Author(s), under exclusive licence to Sociedade Brasileira de Engenharia Naval.
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    Hydrodynamic performance of floating kelp farms: Wave attenuation and coastal protection potential
    (Elsevier Ltd, 2025) Surakshitha; Rao, M.; Rao, S.
    Ecologically rich coastal zone play a crucial role in supporting both biodiversity and the economy. “Soft solutions” for coastal protection, such as vegetated breakwaters and artificial reefs, harness natural features to mitigate coastal erosion. Among these, flexible floating vegetation, such as kelp farms, presents a unique mechanism by altering flow patterns differently than bed-fixed vegetation. This study experimentally investigates the effectiveness of floating kelp farms in dissipating wave energy under monochromatic regular waves. The wave heights ranging from 0.06 m to 0.18 m and periods of 1.6 s–2.8 s is considered. The study examines the effects of two non-dimensional parameters: relative farm width (w/L, 0.1 to 2.5) and relative blade length (l/d, 0.25–1.0), representing the ratios of farm width to wavelength and blade length to water depth, respectively. Under the test conditions investigated, the highest wave dissipation coefficient (Kd ? 0.8) is observed for relative blade lengths of 0.75 and 0.5 at a water depth of 0.45 m. The optimal farm configuration occurred at a relative farm width between 0.3 and 0.4. These findings contribute to a better understanding of the role of kelp farm in wave energy dissipation and highlight its potential as a sustainable alternative for coastal protection. © 2025 Elsevier Ltd