Faculty Publications

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Author: search.filters.author.Hegde, A.V.Subject: search.filters.subject.breakwater

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    Mooring forces in horizontal interlaced moored floating pipe breakwater with three layers
    (2008) Hegde, A.V.; Kamath, K.; Deepak, J.C.
    The paper presents the results from model scale experiments on the study of forces in the moorings of horizontally interlaced, multi-layered, moored floating pipe breakwaters. The studies are conducted with breakwater models having three layers subjected to waves of steepness Hi/L (Hi is the incident wave height and L the wavelength) varying from 0.0066 to 0.0464, relative width W/L (W is the width of breakwater) varying from 0.4 to 2.65, and relative spacing S/D (S is the spacing of pipes and D the diameter of pipe) of 2 and 4. The variation of measured normalized mooring forces on the seaward side and leeward side are analyzed by plotting non-dimensional graphs depicting f/?W2 (f is the force in the mooring per unit length of the breakwater, ? the weight density of sea water) as a function W/L for various values of Hi/d (d is the depth of water). It is found that the force in the seaward side mooring increases with an increase in Hi/L for d/W values ranging between 0.081 and 0.276. The experimental results also reveal that the forces in the seaward side mooring decrease as W/L increases, up to a value of W/L=1.3, and then increases with an increase in W/L. It is also observed that the wave attenuation characteristics of breakwater model with relative spacing of 4 is better than that of the model with relative spacing of 2. The maximum force in the seaward side mooring for model with S/D=4 is lower compared to that for the breakwater model with S/D=2. A multivariate non-linear regression analysis has been carried out for the data on mooring forces for the seaside and leeside. © 2007 Elsevier Ltd. All rights reserved.
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    Neuro-fuzzy based approach for wave transmission prediction of horizontally interlaced multilayer moored floating pipe breakwater
    (2011) Patil, S.G.; Mandal, S.; Hegde, A.V.; Alavandar, S.
    The ocean wave system in nature is very complicated and physical model studies on floating breakwaters are expensive and time consuming. Till now, there has not been available a simple mathematical model to predict the wave transmission through floating breakwaters by considering all the boundary conditions. This is due to complexity and vagueness associated with many of the governing variables and their effects on the performance of breakwater. In the present paper, Adaptive Neuro-Fuzzy Inference System (ANFIS), an implementation of a representative fuzzy inference system using a back-propagation neural network-like structure, with limited mathematical representation of the system, is developed. An ANFIS is trained on the data set obtained from experimental wave transmission of horizontally interlaced multilayer moored floating pipe breakwater using regular wave flume at Marine Structure Laboratory, National Institute of Technology Karnataka, Surathkal, India. Computer simulations conducted on this data shows the effectiveness of the approach in terms of statistical measures, such as correlation coefficient, root-mean-square error and scatter index. Influence of input parameters is assessed using the principal component analysis. Also results of ANFIS models are compared with that of artificial neural network models. © 2010 Elsevier Ltd. All rights reserved.
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    Variation of transmission coefficient and mooring forces with wave steepness on horizontal interlaced multilayered moored floating pipe breakwater with three layers
    (2011) Rajappa, S.; Pramod, K.; Hegde, A.V.; Rao, S.
    The paper presents the results of a series of physical model scale experiments conducted for the study of the transmission characteristics and mooring forces of horizontal interlaced, multi-layer, moored floating pipe breakwater, part of which have been presented in conferences. The studies are conducted on physical breakwater models having three layers of PVC pipes, wave steepness, Hi/L (Hi is incident wave height and L is incident wave length) varying from 0.01384 to 0.0661, relative width, W/L (W is width of breakwater) varying from 0.4 to 2.65 and relative spacing, S/D = 3 (S is horizontal spacing of pipes and D is diameter of pipe). The transmitted wave height is measured and data gathered is analyzed by plotting non-dimensional graphs depicting the variation of Kt (transmission coefficient) with Hi/L for values of d/W (d is depth of water) varying between 0.082 to 0.276 and Kt with W/L for values of d/W varying between 0.082 to 0.221. It is observed that Kt marginally decreases as Hi/L increases for the range of d/W between 0.082 and 0.221, considered in the present study. The maximum wave attenuation achieved with present breakwater configuration is 68%. The variation of measured mooring forces are analyzed by plotting non-dimensional graphs depicting fs/?w2 and fl/?W2 (fs and fl are the forces in the seaside and leeside moorings per unit length of the breakwater, ? is the unit weight of sea water) as a function Hi/L for various values of d/W. The mooring force parameter (fs /?W2) increases with an increase in wave steepness (Hi/L) for a range of d/W values studied. It is observed that for d/W = 0.082, maximum force parameter attained was 2.11E-04, and for d/W = 0.276 maximum force parameter was 6.88E-04. A similar trend is observed for leeside side force parameter. Hence, it clearly indicates the influence of d/W on f/?W2. © 2011 CAFET-INNOVA technical society. All right reserved.
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    Wave steepness and relative width: Influence on transmission coefficient of horizontal interlaced, multilayered, moored floating pipe breakwater with five layers
    (2011) Rajappa, S.; Hegde, A.V.; Rao, S.; Channegowda, V.
    This paper presents the results of a series of physical model scale experiments conducted to determine the transmission characteristics of a horizontal interlaced, multilayered, moored floating pipe breakwater. The studies are conducted on physical breakwater models having five layers of PVC pipes. The wave steepness (H i/gT 2, where H i is incident wave height, g is acceleration due to gravity, and T is time period) was varied between 0.063 and 0.849, relative width (W/L, where W is width of breakwater and L is the wavelength) was varied between 0.4 and 2.65, and relative spacing (S/D, where S is horizontal centre to centre spacing of pipes and D is the diameter of pipes) was set equal to 2. The transmitted wave height is measured, and the gathered data are analyzed by plotting nondimensional graphs depicting the variation of K t (transmission coefficient) with Hi/gT 2 for values of d/W (d is depth of water) and of K t with W/L for values of H i /d. It is observed that K t decreases as H i /gT 2 increases for the range of d/W between 0.082 and 0.139. It is also observed that K t decreases with an increase in W/L values for the range of H i /d from 0.06 to 0.40. The maximum wave attenuation achieved with the present breakwater configuration is 78%.
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    Development of prediction models for hydrodynamic performance of semicircular breakwater
    (2012) Aggarwal, A.; Gope, V.K.; Managiri, S.S.; Hegde, A.V.
    Breakwaters are structures built to protect harbors, shore areas, basins, and other areas from the fury of sea waves. They create calm waters and provide for the safe mooring and handling of ships, as well as protection to harbor facilities. The main function of a breakwater is the formation of an artificial harbor. Of late, certain new types of breakwaters have been constructed to cater to the tranquility requirements of managing marine traffic in ports. The semicircular breakwater (SBW) is one such new type of breakwater. The semicircular breakwater possesses a round top and, thus, offers more stability against the action of waves. It is expected that the SBW will be well suited as an offshore breakwater designed to protect beaches from coastal erosion. A number of experiments were conducted on scaled-down physical models of SBW for different values of parameters such as wave height H, wave period T, spacing of perforations on the seaside, etc. (radius of breakwater and diameter of perforations were kept constant), and data were collected. The paper presents the prediction models/equations for hydrodynamic performance characteristics such as reflection coefficient and relative wave runup, using the data obtained by a regression approach in MATLAB.
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    Transmission studies on horizontal interlaced multi-layer moored floating pipe breakwater (HIMMFPB) with three layers of pipes
    (2013) Hoolihalli, M.V.; Hegde, A.V.
    Present study consists part of the series of physical model scale experiments conducted for the study of the transmission characteristics of horizontal interlaced multi-layer moored floating pipe breakwater (HIMMFPB). Studies were conducted on physical models of the floating breakwater with three layers of PVC pipes, wave steepness, Hi/gT2 (Hi=incident wave height, g=acceleration due to gravity and T=wave period) varying from 0.063 to 0.936; relative width, W/L (W=width of the breakwater) varying from 0.4 to 2.65 and relative spacing of pipes, S/D=2 (S=horizontal c/c spacing of pipes and D=diameter of the pipes). Transmitted wave height is measured and the collected data is analyzed by plotting non-dimensional graphs depicting the variation of Kt (transmission coefficient) with Hi/gT2for various values of d/W (d=water depth) varying from 0.082 to 0.276 and Kt with W/L for different values of Hi/d which was varied from 0.06 to 0.450. It is observed that Kt decreases as Hi/gT2 increases for the range of d/W values used in the study. It is also observed that Kt decreases with an increase in W/L for the range of Hi/d values used. Maximum wave attenuation achieved in the study with the present breakwater configurations is 78.62%.
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    Quarter circular breakwater: Prediction of transmission using multiple regression and artificial neural network
    (Marine Technology Society Inc. mtsdir@erols.com, 2014) Goyal, R.; Singh, K.; Hegde, A.V.
    The physical model study of coastal structures is a nonlinear process influenced by innumerable parameters. As a result of a lack of definite systems, intricacies, and high costs involved in the physical models, we need a simple mathematical tool to predict wave transmission through quarter circular breakwater (QBW). QBW is a state-of-theart breakwater essentially based on the exploitation of the concepts of semicircular breakwater. This paper discusses the use of soft computing tools such as MATLAB based multiple regression (MR) and artificial neural network (ANN) to predict the wave transmission coefficient of QBW. To assess the accuracy of the proposed model and its ability to forecast, correlation coefficient and mean squared error are availed. On comparing the results obtained from MR and ANN, it is concluded that ANN gives more accurate results and can be used as a powerful tool for the modeling of hydrodynamic breakwater transmission through QBW. It serves as a viable alternative to the conventional physical model to simulate the hydrodynamic transmission performance of QBW.
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    Physical model studies on the stability of emerged seaside perforated semicircular breakwaters
    (National Institute of Science Communication and Policy Research, 2018) Hegde, A.V.; Mohan, S.; Pinho, J.L.S.; Sharhabeel, P.S.
    Present study discusses experiments conducted in a two dimensional monochromatic wave flume to determine the critical (minimum) weight required to resist the sliding of an emerged seaside perforated semicircular breakwater model. It is observed from a detailed review that there is hardly any literature, stressing the critical weight determination for the sliding stability of this breakwater type. Hence, the present research was taken up to study the variations in the critical weight required for sliding stability with different wave and structural specific parameters. The variations were recorded graphically using non-dimensional parameters obtained from a dimensional analysis using Buckingham’s ? theorem. © 2018, National Institute of Science Communication and Information Resources (NISCAIR). All rights reserved.