Faculty Publications
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Publications by NITK Faculty
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Item Numerical simulation of oscillating lid driven square cavity(Elsevier B.V., 2018) Indukuri, J.V.; Maniyeri, R.This paper aim to develop a two-dimensional computational model to study the fluid dynamic behaviour in a square cavity driven by an oscillating lid using staggered grid based finite volume method. Firstly the developed computational model is validated with that of other researcher's results for the case of finite wall motion. Later the numerical simulations are performed for the case of top wall oscillations for various combinations of Reynolds number and frequencies. From these simulations an optimum frequency is chosen and then with the optimum frequency the simulations are carried out to explore the vortex behaviour for the cases of parallel wall oscillations (both top and bottom walls moving in the same direction) and anti-parallel wall oscillations (both top and bottom walls moving in the opposite direction). From these simulations it may be concluded that Re = 1000 is medium range of operation for better mixing inside the cavity for the cases of parallel and anti-parallel wall oscillations. © 2017 Faculty of Engineering, Alexandria UniversityItem Electric Field Reduction in an EHV Substation for Occupational Exposure via Transposition of Conductors(Institute of Electrical and Electronics Engineers Inc., 2018) Devarajan, D.; Punekar, G.S.An attempt is made to reduce the maximum value of rms electric field (E-field) via the transposition of conductors in a 765-kV substation with reference to the occupational exposure. The method is applied to a extra-high-voltage substation, which is under construction. The effect of transposing the bay conductors (alone) and the bus conductors (alone) on the E-field distribution (at 2 m above the ground) over the area of the substation is discussed. Also, the topology of substation conductors that results in the minimum value for the maximum of rms E-fields is obtained via simultaneous transpositions of the bus and bay conductors. The area of the substation where the rms E-field exceeds the reference value of 10 kV/m (International Commission on Non-Ionizing Radiation Protection occupational exposure limit) is also reported for the existing topology. For this topology, the computed maximum value of the rms E-field over the area of the substation is 13.06 kV/m. This E-field is reduced to 7.999 kV/m with the best configuration of substation conductors obtained via transposition. The charge-simulation-method-based generalized algorithm for obtaining the best topology (among all permutations) of substation conductors, which results in the minimum value for the maximum of rms E-field magnitudes over the substation area is also reported. © 1986-2012 IEEE.Item Numerical study of forced convection heat transfer in an oscillating lid driven cavity with heated top wall(International Information and Engineering Technology Association info@iieta.org, 2018) Indukuri, J.V.; Maniyeri, R.The present work is aimed to study the fluid flow and heat transfer behaviour in an oscillating lid-driven cavity using finite volume method by developing a two-dimensional computational model. Firstly, the developed computational model is validated by comparing our numerical results with that of the other researcher's results for the case of wall moving with finite motion. Next, the simulations are conducted for oscillating cavity problem with top wall oscillation for Reynolds number (Re =5 00) and frequency (?=2?/6). Later, the simulations are carried out for cases of oscillating parallel wall (upper and lower walls oscillating with sync) and oscillating anti-parallel wall (upper and lower walls oscillating with reverse sync) with the same optimum frequency and fixed Reynolds number (Re = 500). Secondly, the same optimum frequency is used to study the heat transfer characteristics in an oscillating lid-driven square cavity with heated top wall and lower cold wall for various Reynolds numbers (Re = 100-1000) and Prandtl numbers (Pr = 0.2 to 1.0). From this study, it is found that for high Prandtl number case (Pr = 1.0) the flow of high temperature isotherms inside the cavity is more when compared with low Prandtl number cases due to increase in molecular diffusion of momentum. © 2018 International Information and Engineering Technology Association.Item Finite difference method based analysis of bio-heat transfer in human breast cyst(Elsevier Ltd, 2019) Patil, H.M.; Maniyeri, R.Bio-heat transfer is a branch of bio-medical engineering which has its foundation linked to engineering disciplines of heat transfer. The thermal properties and behaviour of various malfunctioning tissues in human body varies as compared with normal tissues. Among various cancer tissues one which is commonly diagnosed in women is breast cyst (cancer causing fluid). The aim of present work is to develop one, two and three-dimensional computational models to study bio-heat transfer problems using finite difference method. First of all, a numerical model based on finite difference method is developed to solve Pennes's bio-heat transfer equation in one-dimension to get temperature profiles normal to skin surface and validated with existing analytical solutions. Secondly, the numerical model is extended to study the thermal behaviour of human breast section embedded with cyst using two-dimensional cylindrical coordinate systems and validated with previous researcher's results. The effect of size, location and presence of multiple cysts on surface temperature is studied. Lastly, the work is extended for the case of three-dimensional breast section with cyst located at the centre. The numerical results obtained using one, two and three-dimensional computational models will be highly helpful in the early detection of breast cancer tissues and also the location of it inside the body. © 2019Item Numerical analysis of the buckling and recuperation dynamics of flexible filament using an immersed boundary framework(Elsevier B.V., 2019) Kanchan, M.; Maniyeri, R.The dynamics of flexible filaments in viscous shear flow is of interest to biologists and engineers in a wide variety of applications involving folding and unfolding sequence of long-chain biomolecules like DNA, non-motile sperm and microalgae. It is also helpful in understanding the deformation of natural and synthetic fibers which can be applied in areas such as biotechnology. In the present work, deformation and migration behavior of non-motile unicellular phytoplankton diatoms subjected to viscous shear flow are considered. These unicellular diatoms develop into colonies which are made up of linked chains. The complex fluid-structure interaction is solved by developing a two-dimensional numerical model with an immersed boundary framework. The simulation consists of suspending an elastic filament mimicking a diatom chain in a shear flow at low Reynolds number. The governing continuity and Navier–Stokes equations are solved on a Cartesian grid arranged in a staggered manner. A forcing term is added to the momentum equation that incorporates the presence of flexible filament in the fluid domain. The discretization of the governing equation is based on a finite volume method, and a SIMPLE algorithm is used to compute pressure and velocity. A computer code is developed to perform numerical simulations, and the model is first verified with the deformation study of a tethered flexible filament in uniform fluid flow. Next, the shape deformations for flexible filament placed freely in shear flow are compared with the studies of previous researchers. Further, the present results are validated with Jeffery's equation for particles immersed in shear flow along with classification plot for filament orbit regimes. All of these comparisons provide a reasonable validity for the developed model. The effect of bending rigidity and shear rate on the deformation and migration characteristics is ascertained with the help of parametric studies. A non-dimensional parameter called Viscous Flow Forcing value (VFF) is calculated to quantify the parametric results. An optimum Viscous Flow Forcing value is determined which indicates the transition of filaments exhibiting either a recuperative (regaining original shape past deformation) or non-recuperative (permanently deformed) behavior. The developed model is successful in capturing fluid motion, diatom buckling, shape recurrences and recuperation dynamics of diatom chains subjected to shear flow. Further, the developed computational model can successfully illustrate filament-fluid interaction for a wide variety of similar problems. © 2019 Elsevier Inc.Item Computational modeling of hydrodynamics and mixing in a batch stirred vessel(Taylor and Francis Ltd., 2021) Falleiro, L.H.; Ali, A.A.In this work, the hydrodynamics, mixing and sedimentation is numerically investigated in the batch stirred vessel through CFD. The flow field obtained by performing transient CFD simulations using multiple reference frame (MRF) and sliding mesh approach along with standard k-? turbulence model. The velocity field is investigated spatially and temporally and liquid circulation is quantified at various impeller speeds to find an optimum impeller speed. The importance of geometry of the draft tube baffles is investigated by quantifying the vorticity, mixing time, power requirement and quality of suspension in the batch stirred vessel. It is found that suspension quantity in a batch stirred vessel is strongly dependent on the hydrodynamics. The role of the draft tube and the inner baffles is further analyzed and found that proper positioning and length of the baffles is necessary to improve the turbulence characteristics and the quality of the suspension. © 2019 Taylor & Francis Group, LLC.Item Numerical consideration of LTNE and darcy extended forchheimer models for the analysis of forced convection in a horizontal pipe in the presence of metal foam(American Society of Mechanical Engineers (ASME), 2021) Jadhav, P.H.; Gnanasekaran, N.; Arumuga Perumal, D.The intent of the current research work is to emphasize the computational modeling of forced convection heat dissipation in the presence of high porosity and thermal conductivity metallic foam in a horizontal pipe for different regimes of the fluid flow for a range of Reynolds number. A two-dimensional physical domain is considered in which Darcy extended Forchheimer (DEF) model is adopted in the aluminum metallic foam to predict the features of fluid flow and local thermal nonequilibrium (LTNE) model is employed for the analysis of heat transfer in a horizontal pipe for different flow regimes. The numerical results are initially matched with experimental and analytical results for the purpose of validation. The average Nusselt number for fully filled foam is found to be higher compared to other filling rate of metallic foams and the clear pipe at the cost of pressure drop. As an important finding, it has been observed that the laminar and transition flow gives higher heat transfer enhancement ratio and thermal performance factor compared to turbulent flow. This work resembles numerous industrial applications such as solar collectors, heat exchangers, electronic cooling, and microporous heat exchangers. The novelty of the work is the selection of suitable flow and thermal models in order to clearly assimilate the flow and heat transfer in metallic foam. The presence of aluminum metal foam is highlighted for the augmentation of heat dissipation in terms of PPI and porosity. The parametric study proposed in this work surrogates the complexity and cost involved in developing an expensive experimental setup. © 2021 American Society of Mechanical Engineers (ASME). All rights reserved.