Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
105 results
Search Results
Item Reef-an ecofriendly and cost effective hard option for coastal conservation(Springer Netherlands, 2008) Shirlal, K.G.; Rao, S.; Radheshyam, B.; Ganesh, V.Rubble mound breakwaters are the structures which are meant to reflect and dissipate energy of the wind generated waves and thereby to prevent their incidence on water area intended to protect. Submerged breakwater with its crest at or below still water level (SWL) can cause substantial wave attenuation and can be effectively used in places where tidal variations are small and only partial protection from waves is required, like harbour entrance, beach protection, small craft harbours etc. © 2008 Springer Netherlands.Item A Review on Stability of Caisson Breakwater(Springer Nature, 2018) Gedda, A.B.; Rao, M.; Rao, S.A Breakwater can be designed for several different purposes; the basic function of such kind breakwater is to protect the water region against waves. It provides a tranquility condition for ships to navigate, moor, and for cargo handling. These vertical structures (caisson) are more economical compared to the rubble mound breakwater, especially in deeper water depths. There is a demand to expand existing ports or to make them more profound, to provide a sufficient tranquil harbor basin in deep-water due to increasing draught of large vessels. The material required for rubble mound breakwaters increase quadratic with depth, but the volume of the caisson is less than that needed for a rubble mound breakwater because the latter increases with the square of water depth. This paper concerned the previous design and failure mechanism on caisson breakwater and highlights the future studies for such kind of breakwater. © Springer Nature Singapore Pte Ltd. 2019.Item Prediction of damage level of inner conventional rubble mound breakwater of tandem breakwater using swarm intelligence-based neural network (PSO-ANN) approach(Springer Verlag service@springer.de, 2019) Kuntoji, G.; Rao, S.; Rao, M.; Reddy, E.N.B.The conventional rubble mound breakwater is a coastal protective structure commonly used decades before which alone failed to withstand the deepwater wave and its energy, and suffered a catastrophic failure. Keeping in mind both the safe functioning of harbor and stability of the breakwater for the fast-growing economy of the country, different types of breakwaters are being developed to serve this purpose. Tandem breakwater is an innovative type of breakwater, which is a combination of main conventional rubble mound breakwater and submerged reef in front of it. One of the advantages of this breakwater is that most of the wave energy is dissipated and wave intensity is reduced by submerged reef and the smaller waves interact with main breakwater and ensure its stability. Experimental studies are laborious and time-consuming to conduct. Therefore, it is necessary to carry out the detailed study of tandem breakwater stability by making use of simple and alternate techniques using the experimental data. In the present study, an attempt is made to understand the suitability and applicability of PSO-ANN, a hybrid soft computing technique for predicting damage level of conventional rubble mound breakwater of tandem breakwater. Based on the experimental data available in Marine Structure Laboratory, NITK, Surathkal, India, soft computing models are developed. The performances of the models are evaluated using model performance indicators. Results obtained demonstrate that the proposed new approach can be used to predict the damage level of conventional rubble mound breakwater of tandem breakwater efficiently and accurately. © Springer Nature Singapore Pte Ltd. 2019Item Prediction of wave transmission over an outer submerged reef of tandem breakwater using RBF-based support vector regression technique(Springer, 2019) Kuntoji, G.; Rao, S.; Rao, M.The development of a mathematical model to determine transmitted wave height over a submerged reef of the tandem breakwater is complex. Therefore, it is necessary for researchers to adopt the physical model study to determine the parameters that influence the performance of breakwaters quantitatively. Physical modelling is laborious, expensive and lengthy in the procedure which makes it inconvenient for immediate needs. From the history, the development of the soft computing model shows that the soft computing techniques can be applied successfully to the prediction of the wave characteristics by making use of experimental data available. Similarly, attempt is made to predict the wave transmission over a submerged reef of tandem breakwater based on the data of Subba Rao developed in 2004 on a tandem breakwater in a 2D wave flume available at NITK Surathkal India using Support Vector Regression (SVR) model with different kernel functions. The non-dimensional input parameters used for the development of the models are five in number. Those inputs are incident wave steepness (Hi/gT2), relative reef crest width (B/Lo), relative reef submergence (F/Hi), relative reef crest height (h/d), depth parameter (d/gT2) and the output as (Ht/Htmax). The 202 data points (70%) are used for training and the 86 data points (30%) for testing out of 288 total data points. The statistical parameters are computed using the predicted and observed data points after training and testing the SVR models. The RBF kernel gives good correlation to the prediction of transmitted wave heights during testing with RMSE as 0.09 and MAE as 0.07. Therefore, the SVR with RBF kernel function can be adopted as an alternative technique to predict the wave characteristics such as wave transmission over a submerged reef of the tandem breakwater. © Springer Nature Singapore Pte Ltd. 2019.Item Nondimensional methods to classify the tidal inlets along the Karnataka coastline, west coast of India(Springer, 2019) Amaranatha Reddy, N.; Mendi, V.; Seelam, J.K.; Rao, S.This classification of tidal inlets is essential to maintain the stability of the inlets as well as to study the changing patterns of tidal inlets in India. Tidal inlets around the world have been classified as either wave-dominated or tide-dominated or river-dominated, since the 1970s. Tidal inlet classification for 471 inlets along the coast of India was carried out by Vikas M et al., based on wave and tide information. But only 30 inlets were considered for river-based classification due to lack of discharge information. In order to consider the river-based classification, the river flood discharge was estimated using Synthetic Unit Hydrograph (SUH) methods for Karnataka coast. In this study, 29 tidal inlets along the coast of Karnataka are selected for the classification based on river discharge. The classification has been done in two aspects; without considering wave period (Formula Presented) where Qtide is peak tidal discharge, Qf is river discharge and H is wave height. The results obtained are validated with hydrological and geomorphological classifications and the dominant forces over the dynamics of the inlets are determined. © Springer Nature Singapore Pte Ltd. 2019.Item Tidal energy estimation of potential tidal inlets along the east coast of India(Springer, 2019) Mendi, V.; Amaranatha Reddy, N.; Seelam, J.K.; Rao, S.The power consumption is increasing with modernization of infrastructure and with the depleting fossil fuels. The need to look for alternate sources of energy generation has already reached a peak. The production of power from renewable energy sources is considered to be on a large scale in the near future because of the abundant sources across the country. One of the most reliable sources is the tidal energy as it can be extracted both by kinetic and potential means at the tidal inlets. The process of extracting tidal potential energy by storing the water during the high tide and release during low water is a well-established method. However, there are many parameters that are to be considered for the potential energy extraction. Two such important parameters, i.e. tidal range and basin area are considered in this study. The interrelationship between these two parameters and its overall influence on potential tidal energy estimation is studied. Along the four coastal states, excluding the Gulfs, around 250 tidal inlets have been identified (Vikas, M.Tech. thesis, 2015 [8]). Considering the standards of existing tidal power plants, tidal energy sites for energy extraction are estimated and will be presented in this paper. © Springer Nature Singapore Pte Ltd. 2019.Item Evaluation of hydrodynamic performance of quarter circular breakwater using soft computing techniques(Springer, 2019) Ramesh, N.; Hegde, A.V.; Rao, S.Breakwaters are massive structures constructed to provide the required tranquility within the ports. They are also used for safeguarding the beaches from eroding due to the severe action of waves, especially during inclement weather. In recent years, innovative structures such as Semi-circular and Quarter-circular Breakwaters (QBW) are being evolved to fulfill the ever-increasing demand from the coastal sector. QBW is a caisson with quarter circular surface towards incident waves, with horizontal bottom and a vertical wall on its rear side placed on a rubble mound foundation. In this paper, the experimental data collected at National Institute of Technology, Surathkal is used. The data collected is analysed by plotting the non-dimensional graphs of reflection coefficient, reflected wave height and incident wave height for various values of wave steepness. The values are used for prediction of QBW adopting Multi-Layer Perceptron (MLP) and Radial Basis Function (RBF) networks. Goodness-of-Fit (GoF) test using Kolmogorov–Smirnov (KS) test statistic is applied for checking the adequacy of MLP and RBF networks to the experimental data. The performance of these networks is evaluated by using Model Performance Indicators (MPIs), viz. correlation coefficient, mean absolute error and model efficiency. The GoF test results and values of MPIs indicated the MLP is better suited amongst two networks adopted for evaluation of hydrodynamic performance of QBW. © Springer Nature Singapore Pte Ltd. 2019.Item Laboratory investigations on the effect of fragmentation and heterogeneity of coastal vegetation in wave height attenuation(Springer, 2019) Shirlal, K.G.; John, B.M.; Rao, S.It has long been known that “bio-shields” do function as a sustainable solution for preserving our coasts. The presence of gaps in the “bio-shield”, that is, the forest cover, referred to as patchiness, is a common phenomenon in natural habitats. Various anthropogenic and natural causes can result in such gaps in coastal forests. This paper presents the results of a physical model investigation carried out with a fragmented heterogeneous vegetation model in a wave flume 50 m long, 0.71 m wide and 1.1 m deep. The heterogeneous meadow is modelled as a combined body of artificial submerged seagrass, rigid vegetation and emergent vegetation. To study the effect of fragmentation in vegetation, transverse gaps of varying widths are introduced in the heterogeneous model. The material used for modelling is polyethylene and nylon. The test runs were carried out with monochromatic waves of heights ranging from 0.08 to 0.16 m in water depths of 0.40 and 0.45 m, and wave periods 1.8 and 2 s. The wave height measurements at different locations within the vegetated meadow exhibit an exponential decay of wave heights. The presence of gaps in vegetation does not have a significant effect on wave height reduction. However, the experimental study revealed that heterogeneous vegetation showed a great promise leading to considerable wave attenuation, thus offering a good level of protection to life and property on the leeside. © Springer Nature Singapore Pte Ltd. 2019.Item Stability Analysis of Emerged Seaside Perforated Quarter Circle Breakwater Using Soft Computing Techniques(Springer Science and Business Media Deutschland GmbH, 2022) Madhusoodhanan, S.; Rao, S.Breakwaters are constructed to address a variety of coastal requirements ranging from maintaining tranquility conditions for a port or harbor area to prevent coastal recession. Quarter circle breakwater (QCB) is a composite structure, with a rubble mound foundation and a super structure comprising of a quarter circular surface facing incident waves resting on a horizontal bottom with a rear vertical wall alongside. Be it any structure, it is essential that the design is economic, safe, and functional. Thus, the accurate estimation of minimum (critical) weight of the super structure required to oppose the sliding is vital. Also, physical model studies can be laborious and time-consuming, whereas numerical modeling can be complex. Therefore, under such circumstances, soft computing techniques prove to be handy if sufficient data are available. In this study, W/γHi 2 of an emerged seaside perforated QCB for varying S/D ratios is estimated using ANN, SVM, and AdaBoost models. Hi/gT2, d/hs, and p (%) are chosen as input parameters with the W/γHi 2 as the output parameter. Further, the obtained results are compared using performance indicators such as RMSE, R2, and MAE following which the best model is selected. The data that are used for the present study is collected from the laboratory investigation conducted in the Wave Mechanics Laboratory of the Department of Water Resources and Ocean Engineering, National Institute of Technology Karnataka, Surathkal. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Synthesis and Characterization of PVDF/Graphene Nanocomposite Membrane for Water Treatment Applications(Trans Tech Publications Ltd, 2022) Rao, S.; Avinash, A.; As, S.; Hegde, C.; Isloor, A.M.; Vinayak, V.R.Membrane technology advancement has gained momentous consideration around the globe because of their appealing highlights, such as effectiveness, low expenses, and effective solutions for longstanding issues in alchemical industries. This study expected to incorporate graphene nanoparticles into Polyvinylidene difluoride (PVDF) to form nanofiltration (NF) layers using DMF (Dimethyl formamide) as solvent via DIPS (diffusion induced phase separation) technique. PVDF polymer membrane performances with varied percent (1 – 6% wt.) of graphene concentrations are studied with Infrared spectral, water uptake, water contact angle, and ion rejection measurements. Scanning electron microscope (SEM) analysis showed that the pore size is often regulated by incorporating graphene nanoparticles (80-90 nm) as compared to PVDF membranes. The PVDF membranes exhibited a relative increase in the contact angle from PVDF to PVDF-G6%, i.e., 50.3° to 63.46 ± .3, thus, showing a relative increase in hydrophobicity. The higher percent of graphene (> 6% by wt.) results in nano-particle accumulation that showed the performances of PVDF/graphene rejection possessing relatively the same results. The results confirmed that the prepared membranes possess an excellent ability to treat wastewater. © 2022 Trans Tech Publications Ltd, Switzerland.