The present scenario of energy market is highly volatile due to large oscillation in the fossil fuel prices. During these periods, the high energy demand for the industries is being partially met ...through non-conventional energy sources such as wind and solar power. The large untapped energy potential in the Ocean is yet to be exploited due to many technological constraints. The recent decades have shown positive developments worldwide towards the ocean wave energy converters. In the present study, an improved wave energy potential estimate has been made. Based on various parameters such as physical site characteristics, environmental conditions and socio-economic regional state, the selection criteria have been suggested. This would form the basis for energy device selection for the decision makers.
•Re-assessment of wave energy potential along Indian coast has been made.•Device selection strategy is proposed based on energy potential, site characteristics and socio-economic aspects.•Few site specific devices have been recommended.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The oscillating water column, OWC device is one of the more promising devices for the extraction of energy from ocean waves. The present study mainly focuses on the influence of bottom profile ...configuration in the OWC on its hydrodynamic performance. Four different bottom profiles flat, circular curve of radius 300 mm, slope of 1:1 and 1:5 were tested in a wave flume. The said models were simultaneously subjected to both regular and random waves. The hydrodynamic performance was studied in terms of wave amplification factor, wave power absorption coefficient, hydrodynamic efficiency, lip wall pressure ratio (pressure at in front of lip wall/pressure due to incident wave) and air pressure ratio (air pressure/pressure due to incident wave). It is found that the natural period of the system was around 1.9 s. The OWC with circular curve bottom profile exhibited a better performance in terms of its effective wave energy conversion and wave amplification factor inside the chamber. The peak magnitude of hydrodynamic efficiency for circular curve bottom profile was 0.71. The performance of the OWC model is found to be better when closer to the natural period of the device.
•The influence of different shapes of bottom profiles inside the OWC chamber on its efficiency is investigated.•An in depth investigation of air vent optimization for conventional flat bottom OWC is carried out.•The efficiency decreases with an increase in wave steepness, due to reflection from lip wall and bottom profile of the OWC.•The natural frequency of the system was observed to be unaltered for different bottom profile configurations.•The OWC with circular curve bottom profile exhibited a better performance in terms of its effective wave energy conversion.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The vulnerability of the tropical cyclonic activities in the Bay of Bengal (BoB) domain are analyzed in terms of its destructive potential. The wave characteristics due to cyclones of varying ...intensities: Vardah, a Very Severe Cyclonic Storm (VSCS); Phethai, a Severe Cyclonic Storm (SCS); and Amphan, the Super Cyclonic Storm (SuCS) in BoB during 2016, 2018, and 2020 causing loss to human life and wealth, are investigated. The input-dissipation source term packages in the spectral wave models under tropical cyclones are studied through (i) integrated parameter, significant wave height, and (ii) individual source term analysis. In addition to the default linear drag coefficient in the wind input source term of van der Westhuysen et al. (2007), two nonlinear formulations of the drag coefficient are included to understand its influence on the source terms. The integrated parameters such as significant wave height are compared with buoy measurements, and the performance of the packages is ascertained through statistical error estimates. Energy contribution from the different source terms under various packages to generate the extreme significant wave height over the domain during the cyclonic period is established. The influence of the drag coefficient on the input source term is found to be pronounced.
•Analyze the characteristics of tropical cyclones in the Bay of Bengal.•Assessment of input-dissipation source term packages at different depths.•Nonlinear drag coefficient formulations are included in wind input source term.•The dominance of nonlinear interactions in wave evolution is established.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
An experimental investigation is conducted to explore the effectiveness of porous baffles placed at l/3 and 2l/3 in the sloshing tank. A tank aspect ratio, hs/l of 0.488 which corresponds to 75% ...filled condition is considered. The sloshing tank is kept inside the freely floating barge and subjected to regular beam sea waves. A wave height of 0.1 m and excitation frequencies ranging from 0.45 Hz to 1.54 Hz is adopted. Baffles with three different porosities of 15%, 20.2% and 25.2% are used. The effectiveness of baffles placed at l/3 and 2l/3 is explored on comparison with the performance of single porous baffle kept at l/2 and a solid submerged baffle place at l/2. Sloshing dynamics for the baffles placed at l/3 and 2l/3 and barge responses are also discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Microplastic particles are found in environmental compartments all over the world and receive a great deal of attention, especially in the aquatic environment. Currently, a particularly high input of ...microplastics via Asian rivers is assumed, but so far, there are hardly any data through field measurements. Three rivers in South India were considered for this purpose to focus on their microplastic load. The emphasis was on the comparison of microplastic concentrations in urban and rural rivers. While two rivers in the megacity Chennai (Tamil Nadu) were found to have an average microplastic concentration of 0.4 microplastic particles/L, a rural river near Munnar (Kerala) had an average concentration of 0.2 microplastic particles/L. Rough estimates of annual microplastic discharge from the Adyar River (Chennai) into the Bay of Bengal are found to be as high as 11.6 trillion microplastic particles. This study should be one of the first baseline studies for microplastic loads in South Indian streams and should be complemented with further environmental sampling before, during and after the monsoon season to get more detailed information on the storage and transportation of fluvial microplastics under different weather conditions.
Swell and wind–seas generally co-exist in the open ocean, and are often difficult to segregate. Swell and wind–sea characteristics of observed wave spectra at off-Kochi, located along India’s ...south-west coast in the Arabian Sea during the south-west monsoon are presented. This paper attempts to split the observed wave spectra into individual wave partitions, thereby enabling the computation of integral wave parameters of each partition. The spectra with five partitions is found occur more frequently in the considered season. To extract wind–sea and swell information from the observed directional spectrum, a consistent overshooting phenomenon (OP), Modified Overshooting phenomenon (MOP) and Wave age (WA) method are employed in each partition. The results show a prevalence of mixed sea states. An analysis from WA method shows the absence of young wind seas. The derived wind–wave parameters of the spectral partitioning algorithm agree well with Toba’s 3/2 law with a good correlation. The effectiveness of interaction between the derived swell and sea components is discussed through nonlinear interactions that are occurring between the set of four waves.
•Swell and wind–sea conditions along the south-west coast of India is made.•Spectral partitioning is done using a scheme based on the energy threshold.•Swell and sea are identified using Overshooting phenomenon and Wave age methods.•The nonlinear interaction between the swell and sea components is established.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Propagation of tropical cyclones and their landfall along the coast affect the livelihood of the coastal community with loss of life, and Bay of Bengal is particularly vulnerable as past disasters ...have shown. The present study investigates the effects of tropical cyclones namely Phailin, Hudhud and Vardah during its landfall along the East Coast of India. Numerical modelling of storm surges primarily depends on the wind characteristics, for which, the performance of the simulated storm surge from cyclone wind and pressure fields of ECMWF is examined with Telemac-2D. The quality of the wind field is enhanced by applying available wind modification techniques, such as the parametric cyclone wind model superposed with ECMWF wind field, and the direct modification of ECMWF wind field. The superposed wind speed is found in good agreement with the measured wind data. The hydrodynamic simulation was then performed for the cyclonic events for the computation of the storm surge. The predictions agree well with the observed surges for the simulations performed with modified wind fields. The error reduced from 15 cm to 6 cm and model skill improved by 3% leading to a correlation coefficient of 0.98.
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BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Dams play a crucial role in meeting growing water demands, generating energy, and flood protection. However, the controlled water release from dams can significantly impact the ecosystem of ...downstream areas, especially estuaries. This study investigated the effects of Sardar Sarovar Dam (SSD) on downstream flow and estimated the flow requirements necessary to support anadromous fish (in this study Tenualosa ilisha) migration in the Narmada River estuary. The study used hydrodynamic modeling and environmental flow requirement analysis methods to arrive at conclusions. The results indicated that the SSD significantly altered the downstream flow patterns, particularly during the monsoon season. A reduced freshwater flow resulted in increased tidal influence. The study found that the optimal discharge rates for fish migration range from 1500 to 2250 m3/s, and the minimum flow required to prevent tidal dominance in the estuary is 500 m3/s. The study underscores the importance of appropriate freshwater release from dams to preserve downstream ecology, support fish migration, and avoid adverse effects on fishing communities.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Destruction of the structures in coastal areas due to an extreme coastal event like a tsunami necessitates the deeper understanding of flow behaviour to improve the design guidelines. The ...characteristics of inland propagating tsunami surge or bore consist of an initial aerated surge or bore tip followed by the gradual increase in water depth (quasi-steady flow phase). During the bore interaction, the structure initially experiences an impulsive pressure, bore pressure followed by quasi-static pressure (quasi-steady flow phase) depending on the ratio of the structure obstruction width to flow channel width (b/W), incoming bore Froude number (Fr), the shape of the structure, and the orientation of structure to the direction of flow. From field surveys and video observations during the 2004 Indian Ocean Tsunami and the 2011 Tohoku tsunami, the structure failure during the quasi-steady state of tsunami flow is found to be predominant. Also, most of the literature in the past focused on the interaction of bore on a single structure in which the flow channelling effect (b/W) is not considered. Thus, the present experimental study gives a detailed insight into the b/W and Fr effect in the force acting on the rectangular structure during the quasi-steady flow of tsunami-like events. To estimate the hydrodynamic force in the quasi-steady flow phase, we have adopted the hydrostatic force equation by incorporating bore height at the structure front (hf) and bore height at the structure back (hr). A simplified semi-analytical method is proposed based on conservation of mass and momentum to estimate the force on the rectangular structures. This approach of force estimation is showed to reasonably predict experimental force-time history. Since design guidelines use the hydrodynamic drag force equation for force estimation, the present study also provides the drag force coefficient (Cd) for b/W > 0.2 and Fr between 0.6 and 2. Along with the consideration of Fr and b/W, the study attempted to provide a closed-form set of equations to the quasi-static force, which helps designers with a convenient force determination method.
•A prediction formula for the the bore height at the structure front and force on the structure based on free flow properties are provided.•A comprehensive experimental study on the effect of flow channelling and Froude number is carried out•The coefficient of drag and coefficient of moment are provided for practical use by designers.•The significance of water depth at the structure front side and backside on the force parameter are discussed.•The study attempted to provide a simplified solution for a 3D flow interaction problem.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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