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Item The evaporative drying of a two-dimensional rectangular brick is studied numerically as a conjugate problem. The conservation equations for the solid are obtained using the continuum approach. The Navier-Stokes equations have been employed for obtaining the flow field and the corresponding flow solutions are used for predicting the drying behavior of the brick. The predictions of temperature and moisture content show that the leading edge dries faster compared to other sides of the solid. The full two-dimensional solutions differ considerably from the solutions based on heat and mass transfer through the boundary layers over the top surface. Average heat and mass transfer coefficients appropriate to the conjugate problem have been defined, based on constant temperature and moisture differentials between the solid and the ambient. The corresponding Nusselt and Sherwood number values indicate that analogy does not exist between heat and mass transfer, until the entire brick reaches wet bulb conditions. Free convection effects on drying are also studied for some initial period for low Reynolds number. Due to the influence of buoyant forces imparted by gravity, the overall drying rate has improved. © 2001 Elsevier Science Ltd. All rights reserved.(Elsevier Ltd, A theoretical model of brick drying as a conjugate problem) Murugesan, K.; Suresh, H.N.; Seetharamu, K.N.; Aswatha Narayana, P.A.; Sundararajan, T.2001Item Rheodynamic lubrication of a squeeze film bearing under sinusoidal squeeze motion(Springer Science and Business Media, LLC, 2007) Kandasamy, A.; Vishwanath, K.P.Lubricants with variable viscosity are assuming importance for their applications in polymer industry, thermal reactors and in biomechanics. With the bearing operations in machines being subjected to high speeds, loads, increasing mechanical shearing forces and continually increasing pressures, there has been an increasing interest to use non-Newtonian fluids characterized by an yield value. The most elementary constitutive equation in common use that describes a material which yields is that of Bingham fluid. In the present work, the problem of a circular squeeze film bearing lubricated with Bingham fluid under the sinusoidal squeeze motion has been analyzed. The shape and extent of the core for the case of sinusoidal squeeze motion has been determined numerically for various values of the Bingham number. Numerical solutions have been obtained for the bearing performances such as pressure distribution and load capacity for different values of Bingham number, Reynolds number and for various amplitudes of squeeze motion. The effects of fluid inertia, non-Newtonian characteristics, and the amplitudes of squeeze motion on the bearing performances have been discussed. Copyright © 2007 SBMAC.Item Simulation of laminar flow in a three-dimensional lid-driven cavity by lattice Boltzmann method(2009) De, S.; Nagendra, K.; Lakshmisha, K.N.Purpose: The purpose of this paper is to apply lattice Boltzmann equation method (LBM) with multiple relaxation time (MRT) model, to investigate lid-driven flow in a three-dimensional (3D), rectangular cavity, and compare the results with flow in an equivalent two-dimensional (2D) cavity. Design/methodology/approach: The second-order MRT model is implemented in a 3D LBM code. The flow structure in cavities of different aspect ratios (0.25-4) and Reynolds numbers (0.01- 1000) is investigated. The LBM simulation results are compared with those from numerical solution of Navier-Stokes (NS) equations and with available experimental data. Findings: The 3D simulations demonstrate that 2D models may predict the flow structure reasonably well at low Reynolds numbers, but significant differences with experimental data appear at high Reynolds numbers. Such discrepancy between 2D and 3D results are attributed to the effect of boundary layers near the side-walls in transverse direction (in 3D), due to which the vorticity in the core-region is weakened in general. Secondly, owing to the vortex stretching effect present in 3D flow, the vorticity in the transverse plane intensifies whereas that in the lateral plane decays, with increase in Reynolds number. However, on the symmetry-plane, the flow structure variation with respect to cavity aspect ratio is found to be qualitatively consistent with results of 2D simulations. Secondary flow vortices whose axis is in the direction of the lid-motion are observed; these are weak at low Reynolds numbers, but become quite strong at high Reynolds numbers. Originality/value: The findings will be useful in the study of variety of enclosed fluid flows.© Emerald Group Publishing Limited.Item Inertia effects in circular squeeze film bearing using Herschel-Bulkley lubricants(2010) Vishwanath, K.P.; Kandasamy, A.Recent engineering trends in lubrication emphasize that in order to analyze the performance of bearings adequately, it is necessary to take into account the combined effects of fluid inertia forces and non-Newtonian characteristics of lubricants. In the present work, the effects of fluid inertia forces in the circular squeeze film bearing lubricated with Herschel-Bulkley fluids with constant squeeze motion have been investigated. Herschel-Bulkley fluids are characterized by an yield value which leads to the formation of a rigid core in the flow region. The shape and extent of the core formation along the radial direction is determined numerically for various values of Herschel-Bulkley number and power-law index. The bearing performances such as pressure distribution and load capacity for different values of Herschel-Bulkley number, Reynolds number, power-law index have been computed. The effects of fluid inertia and non-Newtonian characteristics on the bearing performances have been discussed. © 2009 Elsevier Inc. All rights reserved.Item Transient analysis of subcritical/supercritical carbon dioxide based natural circulation loops with end heat exchangers: Numerical studies(Elsevier Ltd, 2014) Yadav, A.K.; Ram Gopal, M.; Bhattacharyya, S.Transient analysis of carbon dioxide based natural circulation loop (NCL) with end heat exchangers has been carried out. Subcritical and supercritical phases of CO2 are considered with operating pressures in the range of 50-100 bar for an operating temperature range of 323 K to 363 K. Studies are carried out for various loop tilt angles, different initial conditions, and different water mass flow rates. Results: are obtained for various inlet temperatures of water in the hot heat exchanger while keeping the inlet temperature of cooling water in the cold heat exchanger fixed. Effect of tilting the loop in XY and YZ planes on transient as well as steady state behaviour of loop are also studied. Validation of simulation results against experimental and numerical results reported in the literature in terms of modified Grashof number (Grm) and Reynolds number (Re) show good agreement. © 2014 Elsevier Ltd. All rights reserved.Item Effect of preheated mixture on heat transfer characteristics of impinging methane-air premixed flame jet(Elsevier Ltd, 2015) Tajik, A.R.; Kuntikana, P.; Prabhu, S.V.; Hindasageri, V.Energy from spent flame or other low grade energy can be used to increase the temperature of the air before mixing with fuel. This would improve the heat transfer characteristics of the impinging flame jet. The studies on impinging flame jets reported in the literature are based on the fuel-air mixture at ambient temperature. In the present work, the inlet air for mixture is heated by an electrical heater. The heat flux distribution is estimated using an inverse heat conduction (IHCP) technique. The Nusselt number (Nu) and effectiveness (?) distributions are obtained by estimating the adiabatic wall temperature (Taw) by the analytical-numerical method. A circular burner of 13.5 mm is used for impingement on quartz plate of 3 mm thickness. Reynolds number (Re) varying from 500 to 2000 for the non-dimensional burner tip to impingement plate spacing (Z/d) of 2-6 and stoichiometric condition (Ø = 1.0) is considered for varying preheated condition. The effect of equivalence ratio is studied for Ø = 0.75 to 1.5 for Re = 1000 and Z/d = 4. By increase in preheat temperature, the stagnation point heat flux increases from 20% to 50% unless the inner premixed zone touches the impingement plate. CFD simulations are carried out in FLUENT software to explain the distribution of heat flux. © 2015 Elsevier Ltd. All rights reserved.Item A numerical investigation on heat transfer and emissions characteristics of impinging radial jet reattachment combustion (RJRC) flame(Elsevier Ltd, 2015) Tajik, A.R.; Hindasageri, V.Radial Jet Reattachment combustion (RJRC) flame jet is used in applications where the impingement surface is delicate and demands low impingement pressure. In the present study, a two dimensional axisymmetric computational fluid dynamics (CFD) simulation is carried out. The turbulence-combustion interaction in the flame field is modeled in a k-?/EDM framework. The distribution of heat flux, pressure coefficient and emissions is presented for varying Reynolds number (Re = 1000 to 30,000) and different non-dimensional nozzle tip to plate spacing (X/R = 0.5 to 3). It is found that the peak heat flux increases and pressure coefficient reduces significantly with the increase in Reynolds number. However, with the increase in the nozzle tip to plate spacing the peak heat flux and the pressure coefficient decrease. Furthermore, the concentrations of NOx and CO emissions increase with the increase in Reynolds number and the distance of the location of the nozzle tip from the impingement plate. © 2015 Elsevier Ltd. All rights reserved.Item Computational fluid dynamic approach to understand the effect of increasing blockage on wall shear stress and region of rupture in arteries blocked by arthesclerotic plaque(UK Simulation Society Clifton Lane Nottingham NG11 8NS, 2016) Hegde, S.S.; Deb, A.; Nagesh, S.Computational bio-mechanics is developing rapidly as a non-invasive tool to assist the medical fraternity to help in both diagnosis and prognosis of human body related issues such as injuries, cardio-vascular dysfunction, atherosclerotic plaque etc. Any system that would help either properly diagnose such problems or assist prognosis would be a boon to the doctors and medical society in general. This project is an attempt to use numerical analysis techniques; in particular, computational fluid dynamics (CFD) to solve hemodynamics related problems. The mathematical modeling of the blood flow in arteries in the presence of successive blockages has been analyzed using CFD technique. Different cases of blockages in terms of percentages have been modeled to study the effect of blockage on wall shear stress values and also the effect of increase in Reynolds number on wall shear stress values. The concept of fluid structure interaction (FSI) has been used to study the effect of increasing von Mises stress on arteries and to determine the region of rupture in arteries. The simulation results are validated using in vivo measurement data from existing literature. © 2016, UK Simulation Society. All rights reserved.