Journal Articles
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Item A class of two-step implicit methods involving higher-order derivatives of y for initial value problems of the form y? = f(t, y, y?)is developed. The methods involve arbitrary parameters p and q, which are determined so that the methods become absolutely stable when applied to the test equation y? + ?y? + ?y = 0. Numerical results for Bessel's and general second-order differential equations are presented to illustrate that the methods are absolutely stable and are of order O(h4), O(h6) and O(h8).(Elsevier, Obrechkoff methods having additional parameters for general second-order differential equations) Sesappa Rai, A.; Ananthakrishnaiah, U.1997Item Capacitance computation is an important step in the development of a spacecraft equivalent circuit model for predicting the surface charge build up. Since different parts of the spacecraft may be represented in terms of standard geometrical shapes, this paper presents a numerical procedure developed for computing the capacitance of such standard objects located in free space. The objects considered are conducting and hence the analysis assumes an equipotential surface having an unknown charge distribution. The charge distribution and the total charge are evaluated using the moment method by triangular patch modelling of the surface. The capacitance in free space of planar, cubic and wedge shaped conducting geometries have been numerically computed using the above technique. The results obtained for some of these geometries have been compared with the results available in the literature.(Free space capacitance of conducting surfaces) Hariharan, V.K.; Shastry, S.V.K.; Chakraborty, A.; Katti, V.R.1998Item Stress analysis of SUS 304 - Ceramics functionally graded beams using third order shear deformation theory(2008) Akhtar, K.; Kadoli, R.Kinematics for moderately thick rectangular beams satisfying zero shear strain on the top and bottom . surfaces is utilized to define the strain displacement relations involving the membrane, bending and higher order of displacements. Strain energy containing shear rotation term is deduced. The principle of stationary potential energy is used to obtain the static finite element equilibrium equations for the FGM (functionally graded material) beam with a uniformly distributed transverse load. FGM beams with continuous and smooth grading of metal and ceramics based on po wer law index are considered for the study. Equivalent single layer approach is followed for the evaluation of the constitutive matrix of the FGM beam. Numerical results are presented on the axialstresses and shear stresses in SUS304-Al3O3, SUS 304-ZrO2 and SUS 304-Si3N4FGM beams with clamped-clamped and simply supported boundary conditions. The effect of volume fraction of ceramic and metal on the nature of stress distribution through the thickness are investigated. The studies reveal that, the magnitude and distribution profile of static stresses in the beam depends on the power law index and also on the nature of load bearing surface, ie, whether the loading is on the ceramic rich face of the beam or metal rich face.Item Numerical simulation of laminar flow past a circular cylinder(2009) Rajani, B.N.; Kandasamy, A.; Majumdar, S.The present paper focuses on the analysis of two- and three-dimensional flow past a circular cylinder in different laminar flow regimes. In this simulation, an implicit pressure-based finite volume method is used for time-accurate computation of incompressible flow using second order accurate convective flux discretisation schemes. The computation results are validated against measurement data for mean surface pressure, skin friction coefficients, the size and strength of the recirculating wake for the steady flow regime and also for the Strouhal frequency of vortex shedding and the mean and RMS amplitude of the fluctuating aerodynamic coefficients for the unsteady periodic flow regime. The complex three dimensional flow structure of the cylinder wake is also reasonably captured by the present prediction procedure. © 2008 Elsevier Inc. All rights reserved.Item Influence of masonry infill on fundamental natural frequency of 2D RC frames(2010) Chethan, K.; Ramesh Babu, R.; Venkataramana, K.; Sharma, A.Reinforced Concrete (RC) framed structures with Un-Reinforced Masonry (URM) infill panels form a major portion of all the RC framed structures worldwide. The URM panels are considered as non-structural members, which is fairly good assumption under gravity loads, however, it is not the same under lateral forces. Under seismic loads, the stiffness additions due to infill panels modify the dynamic behavior of the structure significantly by altering the frequency of the structure. A research project has been taken up at Earthquake Engineering and Vibration Research Centre (EVRC), Central Power Research Institute (CPRI), Bangalore to investigate the influence of masonry infill on fundamental natural frequency of RC frames. 2D RC frames of one bay and two bay having single storey, double storey and three storeys are cast and tested for bare frame and many combinations of URM infill panels. Tri-axial shake table is used for testing. The details of the numerical analysis and experimentation carried out in the research project are brought out in this paper.Item Study on shelter effect of solid wind fences(2011) Umesh, U.; Prashanth, J.; Yaragal, S.C.; Nagaraj, M.K.In this paper the shelter effect of solid wind fence is investigated. A solid fence was considered with different bottom gap ratios (ratio of bottom gap to the height of the fence) of 0, 0.1, 0.2 and 0.3. The numerical analysis was done for different free stream velocities of 7.5 m/s, 10 m/s and 12.5 m/s. The results obtained were compared with the results of wind tunnel testing and flow visualization. Comparison between the experimental and numerical results showed a fairly good agreement. Flow visualization technique provided sufficient information for planning and conducting flow field measurements with a clear demarcation of reattachment length. The modified k- ? turbulence model predicted the flow well. From both the experimental and numerical investigation it is shown that a fence with gap ratio of 0.1 is effective in providing good shelter effect. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.Item Numerical Analyses of Single-Phase Pressure Drop and Forced Convective Heat Transfer Coefficient of Water–Ethanol Mixture: An Application in Cooling of HEV Battery Module(John Wiley and Sons Inc. P.O.Box 18667 Newark NJ 07191-8667, 2016) Suhas, B.G.; Sathyabhama, A.The present numerical analyses are related to the cooling of a hybrid electric vehicle (HEV) battery module by water–ethanol mixture. The fluid is passed through a cold plate consisting of two rectangular channels of 0.01 m depth, 0.015 m width, and 0.15 m length. The battery module is represented by a heater placed below the cold plate. The single-phase pressure drop and single-phase heat transfer coefficient for water, water–ethanol mixture of mass fraction of 25%, 50%, and 75%, and ethanol are determined numerically for different heat fluxes of 10, 15, 20, and 25 kW/m2 and different Reynolds numbers 500, 1000, 1500, 2000, and 2500. To solve the Navier–Stokes equation, the pressure correction method was used and to solve the energy equation, the Lax–Wendroff explicit method is used. Numerical results obtained for water are compared with the literature correlations. The friction factor for water deviated by an average of 8.02% from the Lewis and Robertson equation. The Nusselt number for water deviated by 7.35% from the Churchill and Ozoe equation at lower Reynolds number 500 and at higher Reynolds number 2500, Nusselt number deviated by 13.68% from the Stephan equation. The results showed that the heat transfer coefficient increased with an increase in Reynolds number and heat flux. The effect of the increase in Reynolds number is more significant than the increase in heat flux. At higher ethanol mass fraction and higher Reynolds number the heat transfer coefficient increased with heat flux when compared to water. There is no significant decrease in heat transfer coefficient with an increase in ethanol mass fraction. The pressure drop increased and the heat transfer coefficient decreased with an increase in ethanol mass fraction. © 2015 Wiley Periodicals, Inc.Item Numerical and experimental investigation of melting characteristics of phase change material-RT58(Elsevier Ltd, 2020) Yadav, A.; Donepudi, T.; Siddani, B.S.The present study is focused on experimental and numerical analysis of unconstrained melting of Paraffin wax-RT58 in a horizontally placed cylindrical container. After the validation of numerical model with experimental results, numerical analysis is extended to constrained melting to investigate the process. The experiments are carried out at constant wall temperature maintained on the lateral surface of the cylinder. The influence of initial sub-cooling and lateral surface temperature on the melting rate is investigated. The melting process is better analyzed by the melting phase front and temperature contours as time progresses. The results show that the melting rate decreases by increasing the initial sub-cooling, and increases with increasing lateral surface temperature of the cylinder. In unconstrained melting, heat transfer by conduction governs the melting process initially, but later it is restricted to only the bottom part of the cylinder as the solid PCM at a higher density sinks due to effects of gravity. Heat transfer in the upper half of the cylinder is dominated by natural convection set up in the liquid PCM. In constrained melting, pure conduction phenomenon exists only in the beginning, and later conjugate heat transfer occurs. When subjected to similar boundary conditions, PCM melt-time is lower in unconstrained melting than in constrained melting. A correlation between melt-time and Stefan number is also developed. © 2019 Elsevier LtdItem Stress analysis between tunnel and slope for single as well as multiple tunnel scenarios: A numerical modelling approach(Indian Academy of Sciences, 2020) Nikumbh, R.K.; Ram Chandar, K.R.Nowadays, a wide accessible network requires a combination of tunnels and roads through highly undulating surfaces. This study aims to assess the stress due to surrounding slope on a tunnel using ANSYS software. A circular tunnel with varying distance between the tunnel and slope, and berm width has been used for the analysis. For multiple tunnel cases, distance between the tunnels was also varied for assessing stresses. In this study, maximum and minimum stresses were obtained for a berm width of 4 and 7 m respectively, which showed that stress decreases with an increase in berm width. For multiple tunnels cases, variations in distance between two tunnels provided significant insights in the analysis of stress between the slope and tunnel. © 2020, Indian Academy of Sciences.Item Numerical analysis of polymer composites for actuation(International Information and Engineering Technology Association, 2020) Hiremath, S.; Sangappa, V.; Rajole, S.; Kulkarni, S.M.The design of a polymer composite actuator is essential for micro and nano applications. Thus, the composite material may deform or deflects as specific stimuli are applied, such as heat, electrical, light source, etc. The deformation of the composite material is caused by the type of stimulus applied. Hence, while it is heated, the expansion takes place quickly, and the heating is shut down, the material shrinks very slowly. In the present investigation, this phenomenon is mainly studied in the actuation of composite beams. Numerical analysis of carbon black filled polymer composite beam expansion, and contraction is being analyzed in this research. The structure of the beam has been created, and the composite properties are incorporated into the beam, and the uniform heat source is applied on to the surface of the beam. The heating and cooling of the composite material predict the increase and decrease in the temperature of the beam. The numerical analysis of the temperature-dependent expansion and contraction of the composite beam has been carried out successfully. An increase in temperature is observed to signify the slight expansion in the composite beam, whereas the contraction of the composite beam takes a longer time to reach room temperature. Also, the increase in the content of the filler leads to a decrease in the expansion of the composite beam. The numerical simulation of the polymer composite thus provides a solid platform for the experimental study of thermal actuators. © 2020 Lavoisier. 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