Faculty Publications
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Item Classification of tidal inlets along the central east coast of India(Elsevier Ltd, 2015) Reddy, N.A.; Mendi, M.; Rao, S.; Seelam, J.K.Coastal inlets are the openings along the coastline that provide a linkage between the open ocean and the hinterland water bodies. These coastal inlets are varied in nature depending on many influencing parameters such as tide, wind, river flow and waves. Amongst these parameters, the tides are the most regular while waves and freshwater flow are more seasonal. The tidal inlets have to be examined and studied to understand the nearshore coastal processes. The inlet remains stable (i.e. open) as long as the alongshore sediment bypasses the tidal inlet. Classification of coastal systems in a broader view is necessary for the management of tidal inlets. There are several methods to classify tidal inlets based on different perspectives namely geo-morphological, hydrodynamic etc. In the present study, tidal inlet classification is carried out considering the hydrodynamics and morphodynamics along the Andhra Pradesh coast, considering the classification method as in Hayes (1984) and Thuy (2013). The Hayes (1984) classification considers only the tidal range and significant wave height, whereas Thuy (2013) considers discharge due to tide (∼Tidal prism/tide duration) and wave (∼√gH5). A total of 108 tidal inlets along Andhra Pradesh coast on the east coast of India are classified considering annual mean wave height (Hs) as well as seasonal wave heights. This paper presents the methods used and results of the coastal classification along the central east coast of India. © 2015 Published by Elsevier Ltd.Item The objective of the present study is to predict analytically the material perforation under hyper velocity impact. Hyper velocity impact is a complex phenomenon involving wave propagation, penetration and responses exceeding elastic limits, leading to hydrodynamic behaviour. A general-purpose program (GPP) that permits a combination of non-linear finite element technique and explicit integration scheme, is employed for the simulations. The geometry of perforation is computed for various projectiles with different incident angles, impact velocities and materials. The computed values are compared with test results available in the literature. The results indicate excellent agreement with the measurements and give good insight into the effect of various parameters on the perforation size and geometry.(Perforation under hyper velocity impact - A prediction using finite element technique) Suhas, M.; Samgeeth, R.; Veenaranjini, S.M.; Singh, G.2005Item Stability of breakwater defenced by a seaward submerged reef(2006) Shirlal, K.G.; Rao, S.; Ganesh, V.; Rao, M.The stability of a uniformly sloped conventional rubble mound breakwater defenced by a seaward submerged reef is investigated using physical model studies. Regular waves of wide ranging heights and periods are used. Tests are carried out for different spacings between two rubble mound structures (X/d=2.5-13.33) and for different relative heights (h/d=0.625-0.833) and relative widths (B/d=0.25-1.33) of the reef. It is observed that a reef of width (B/d) of 0.6-0.75 constructed at a seaward distance (X/d) of 6.25-8.33 breaks all the incoming waves and dissipates energy and protects the breakwater optimally. © 2005 Elsevier Ltd. All rights reserved.Item Hydrodynamics characterization of a counter-current spray column for particulate scrubbing from flue gases(2008) Biswas, S.; Rajmohan, B.; Meikap, B.C.Growing environmental concern and tightening of the regulations for particulate emission from various sources force us to think of an alternative technology for their control, which is cost effective and of high performance. A spray column using a wet process to control the particulates offers design simplicity, and has various other advantages over other conventional equipment used in industry. This work presents the hydrodynamic study of the spray column for the removal of particulates from gaseous wastes. Experiments were carried out to quantify pressure drop (?P), for varied gas and liquid rates ranging from 3.084 × 10-3 to 5.584 × 10-3 Nm3/s and 8.35 × 10-6 to 33.34 × 10 -6 m3/s, respectively with QL/QG ratio ranging from 1.59 to 10.81 m3 per 1000 ACM (actual cubic meter). The maximum pressure drop incurred in the column is 327 N/m3, which is at a gas rate of 5.584 × 10-3 Nm3/s, liquid rate of 33.34 × 10-6 m3/s, and an inlet solid loading range of 0-2.5 kg/m3. This is quite low compared to other wet process-based equipment, thus making it a low power loss scrubber. These results have further demonstrated the impact of solid dust (particulates) on the pressuredrop-hydrodynamics. A correlation was put forward for prediction of the overall pressure drop in the column. The experimental values agreed well with the predicted values, with minimum percentage error and standard deviation. © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.Item Miscibility of polymethylmethacrylate and polyethyleneglycol blends in tetrahydrofuran(2009) Muthu, M.S.; Bhat, D.K.; Renganathan, N.G.The miscibility of polymethylmethacrylate (PMMA) and polyethyleneglycol (PEG) blends in tetrahydrofuran. (THF) has been investigated by viscosity, density, refractive index, and ultrasonic velocity studies. Various interaction parameters such as polymer-solvent and blend-solvent interaction parameters and heat of mixing have been calculated using the viscosity, density, and ultrasonic velocity data. The results indicated the existence of positive interactions in the blend polymer solutions and that they are miscible in THF in the entire composition range. The study also revealed that variation in the temperature does not affect the miscibility of PMMA and PEG blends in THF significantly. The presence of hydrogen bonding in the blends in the solid state has also been indicated by FTIR studies. © 2008 Wiley Periodicals, Inc.Item A novel procedure for determination of hydrodynamic pressure along upstream face of dams due to earthquakes(2010) Gogoi, I.; Maity, D.The estimation of hydrodynamic pressures along the upstream face of the dam is a critical parameter for the accurate analysis and design of a dam. The accurate estimation of the hydrodynamic pressures necessitates the consideration of interaction between the dam, the reservoir and the foundation. The interaction effects of the unbounded domain of the reservoir and the absorptive materials deposited at the reservoir bottom are frequency dependent which can be incorporated in a frequency domain procedure easily. But in a time domain procedure the frequency dependent interaction effects are lost. In a frequency domain solution, the excitation frequencies are extracted from the earthquake signal using a Fourier transformation, but do not give any information about how it varies with time. To overcome this, a short-time Fourier transform based formulation is presented in this paper to evaluate the hydrodynamic pressures in time domain to account for the frequency dependent interaction effects of the dam-reservoir system. Thus, the adequate accuracy in the determination of hydrodynamic pressure under earthquake excitation is ensured with the proposed truncation boundary condition. © 2010 Elsevier Ltd. All rights reserved.Item 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.Item The combined effects of carbon/nitrogen ratio, suspended biomass, hydraulic retention time and dissolved oxygen on nutrient removal in a laboratory-scale anaerobic–anoxic–oxic activated sludge biofilm reactor(IWA Publishing, 2018) Manu, D.S.; Thalla, A.K.The current trend in sustainable development deals mainly with environmental management. There is a need for economically affordable, advanced treatment methods for the proper treatment and management of domestic wastewater containing excess nutrients (such as nitrogen and phosphorus) which can cause eutrophication. The reduction of the excess nutrient content of wastewater by appropriate technology is of much concern to the environmentalist. In the current study, a novel integrated anaerobic–anoxic–oxic activated sludge biofilm (A2O-AS-biofilm) reactor was designed and operated to improve the biological nutrient removal by varying reactor operating conditions such as carbon to nitrogen (C/N) ratio, suspended biomass, hydraulic retention time (HRT) and dissolved oxygen (DO). Based on various trials, it was seen that the A2O-AS-biofilm reactor achieved good removal efficiencies with regard to chemical oxygen demand (95.5%), total phosphorus (93.1%), ammonia nitrogen concentration (NH4þ-N) (98%) and total nitrogen (80%) when the reactor was maintained at C/N ratio of 4, suspended biomass of 3 to 3.5 g/L, HRT of 10 h, and DO of 1.5 to 2.5 mg/L. Scanning electron microscopy (SEM) of suspended and attached biofilm showed a dense structure of coccus and bacillus bacteria with the diameter ranging from 0.3 to 1.2 ?m. The Fourier transform infrared (FTIR) spectroscopy results indicated phosphorylated macromolecules and carbohydrates mix or bind with extracellular proteins in exopolysaccharides. © IWA Publishing 2018.Item Hydroelastic analysis of articulated floating elastic plate based on Timoshenko–Mindlin plate theory(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2018) Praveen, P.; Karmakar, D.; Guedes Soares, C.G.The wave interaction with articulated floating elastic plate is investigated considering the Timoshenko–Mindlin thick plate theory for both finite and shallow water depths. The elastic plates are modelled as finite flexible floating structure interconnected with vertical linear/rotational spring stiffness. The eigenfunction expansion method along with the orthogonal mode-coupling relation is used to analyse the hydrodynamic behaviour of the interconnected structure. The study is performed for different articulated edge conditions for varying plate thickness and water depths to understand the behaviour of articulation under the action of an ocean wave. The hydroelastic response of the interconnected floating elastic plate with different connector stiffness is observed to compare well with the result available in the literature. The present study provides an insight into the effect of articulated joints with varying spring stiffness for the suitable design of the structure. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.Item Computational investigation of hydrodynamics and solid circulation in fluidized bed column(Taylor and Francis Ltd., 2021) Sriniketh, A.; Ali, A.A.Gas–solid fluidized beds are commonly used in applications where high heat and mass transfer is required, which are influenced by the quality of mixing in the bed. This largely depends on the design of gas distributor and operating conditions. Hence, in the current work, the influence of distributor design on hydrodynamics in a 3D bubbling fluidized bed column is investigated using CFD. Here, Euler-Euler model is used to predict the flow field. The predicted bed pressure drop is analyzed for various superficial gas velocities, and it has been validated with the experimental data. The solid circulation rate is calculated to quantify the flow field, and it is improved by incorporating various gas distributors such as flat, convex and concave perforated plates. The magnitude of solid circulation rate is found to be the highest for convex plate, showing that it is more advantageous than the conventional flat plate configuration. Further, the effect of operating temperature and the influence of baffle on gas–solid flow are analyzed. The rate of solid circulation is found to decrease with increase in temperature and in the presence of baffle. © 2019 Taylor & Francis Group, LLC.