1. Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/1/5
Browse
10 results
Search Results
Item Rheodynamic lubrication of a squeeze film bearing under sinusoidal squeeze motion(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 Rheodynamic lubrication of an externally pressured thrust bearing using herschel-bulkley fluid with sinusoidal injection(2012) Amalraj, I.J.; Narasimman, S.; Kandasamy, A.Lubricants with variable viscosity are assuming greater importance for its application in polymer industry, thermal reactors and in biomechanics. With the bearing operations in machines being subject to high speeds, loads, increasing mechanical shearing forces and continually increasing pressure, there has been an increasing interest to use non-Newtonian fluids characterized by a yield value. Some of them, which fit into this class, are Bingham, Casson and Herchel-Bulkley models. In the present work, the problem of an externally pressurized thrust bearing lubricated with Herschel-Bulkley fluid under the sinusoidal flow rate has been investigated. Herschel-Bulkley fluids are characterized by a yield value, which leads to the formation of rigid core in the flow region. The shape and extent of the core has been determined numerically for various values of the Herschel-Bulkley number, power-law index, amplitude of sinusoidal fluid film and time. Numerical solutions have been obtained for the bearing performances such as pressure distribution and load capacity for different values of the Herschel-Bulkley number, power-law index, amplitude of sinusoidal fluid film and time. The effects of sinusoidal injection of the lubricant and the non-Newtonian characteristics on the bearing performances have been discussed.Item On the reliability of eddy viscosity based turbulence models in predicting turbulent flow past a circular cylinder using URANS approach(2012) Rajani, B.N.; Kandasamy, A.; Majumdar, S.Turbulent flow past circular cylinder at moderate to high Reynolds number has been analysed employing an secondorder time accurate pressure-based finite volume method solving two-dimensional Unsteady Reynolds Averaged Navier Stokes (URANS) equations for incompressible flow, coupled to eddy-viscosity based turbulence models. The major focus of the paper is to test the capabilities and limitations of the present turbulence model-based 2D URANS procedure to predict the phenomenon of Drag Crisis, usually manifested in reliable measurement data, as a sharp drop in the mean drag coefficient around a critical Reynolds number. The computation results are compared to corresponding measurement data for instantaneous aerodynamic coefficients and mean surface pressure and skin friction coefficients. Turbulence model-based URANS computations are in general found to be inadequate for correct prediction of the mean drag coefficients, the Strouhal number and also the coefficients of maximum fluctuating lift over the range of flow Reynolds number varying from 10 4 to 10 7.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 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 Node - Link disjoint multipath routing protocols for wireless sensor networks - A survey and conceptual modeling(2012) Muni, Venkateswarlu, K.; Chandra, Sekaran, K.; Kandasamy, A.There are different ways to classify the routing protocols that are available. The paper presented here discusses different types of multipath routing protocols for Wireless sensor networks based on the parameter "Disjointedness". In this paper, First, WSN routing issues are discussed then listed the advantages of Multipath routing. Further, comprehensive study of different types of WSN Disjoint-multipath routing protocols is given. Finally, some of the WSN multipath routing on-going research issues are listed. � 2012 Springer-Verlag.Item Inference of Gene Networks from Microarray Data through a Phenomic Approach(2010) D'Souza, R.G.L.; Chandra, Sekaran, K.; Kandasamy, A.The reconstruction of gene networks is crucial to the understanding of cellular processes which are studied in Systems Biology. The success of computational methods of drug discovery and disease diagnosis is dependent upon our understanding of the biological basis of the interaction networks between the genes. Better modelling of biological processes and powerful evolutionary methods are proving to be a key factor in the solution of such problems. However, most of these methods are based on processing of genotypic information. We present an evolutionary algorithm for inferring gene networks from expression data using phenotypic interactions. The benefit of this is that we avoid the need for an explicit objective function in the optimization process. In order to realize this, we have implemented a method called as the Phenomic algorithm and validated it for stability and accuracy in the reconstruction of gene networks. � Springer-Verlag Berlin Heidelberg 2010.Item A phenomic approach to genetic algorithms for reconstruction of gene networks(2010) D'Souza, R.G.L.; Chandra, Sekaran, K.; Kandasamy, A.Genetic algorithms require a fitness function to evaluate individuals in a population. The fitness function essentially captures the dependence of the phenotype on the genotype. In the Phenomic approach we represent the phenotype of each individual in a simulated environment where phenotypic interactions are enforced. In reconstruction type of problems, the model is reconstructed from the data that maps the input to the output. In the phenomic algorithm, we use this data to replace the fitness function. Thus we achieve survival-of-the- fittest without the need for a fitness function. Though limited to reconstruction type problems where such mapping data is available, this novel approach nonetheless overcomes the daunting task of providing the elusive fitness function, which has been a stumbling block so far to the widespread use of genetic algorithms. We present an algorithm called Integrated Pheneto-Genetic Algorithm (IPGA), wherein the genetic algorithm is used to process genotypic information and the phenomic algorithm is used to process phenotypic information, thereby providing a holistic approach which completes the evolutionary cycle. We apply this novel evolutionary algorithm to the problem of elucidation of gene networks from microarray data. The algorithm performs well and provides stable and accurate results when compared to some other existing algorithms. � 2010 Springer-Verlag Berlin Heidelberg.Item A phenomic algorithm for inference of gene networks using S-systems and memetic search(2012) D'Douza, R.G.L.; Sekaran, K.C.; Kandasamy, A.In recent years, evolutionary methods have seen unprecedented success in elucidation of gene networks, especially from microarray data. We have implemented the Phenomic Algorithm which is an evolutionary method for inference of gene networks based on population dynamics. We have used S-systems to model gene interactions and applied memetic search to fine tune the parameters of the inferred networks. We have tested the novel algorithm on artificial gene expression datasets obtained from simulated gene networks. We have also compared the results to those obtained from two other similar algorithms. Results showed that the new method, which we call as Phenomic Algorithm with Memetic Search (PAMS), is an effective method for inference of gene networks. � 2012 ICST Institute for Computer Science, Social Informatics and Telecommunications Engineering.Item A multiobjective phenomic algorithm for inference of gene networks(2012) D'Souza, R.G.L.; Sekaran, K.C.; Kandasamy, A.Reconstruction of gene networks has become an important activity in Systems Biology. The potential for better methods of drug discovery and of disease diagnosis hinge upon our understanding of the interaction networks between the genes. Evolutionary methods are proving to be successful in such problems and a number of such methods have been proposed. However, all these methods are based on processing of genotypic information. We have presented an evolutionary algorithm for reconstructing gene networks from expression data using phenotypic interactions, thereby avoiding the need for an explicit objective function. Specifically, we have also extended the basic phenomic algorithm to perform multiobjective optimization for gene network reconstruction. We have applied this novel algorithm to the yeast sporulation dataset and validated it by comparing the results to the links found between genes of the yeast genome at the SGD database. � 2012 ICST Institute for Computer Science, Social Informatics and Telecommunications Engineering.