http://hdl.handle.net/2262/9898 2013-05-19T18:57:51Z http://hdl.handle.net/2262/23960 Title: Study of Parallel implementation of Computational codes Author: Tyagi, Shekhar Abstract: The use of computers to solve scientific problems is abundant and almost a need of the day. As the complexity of the problems increased, the need to get fast and accurate results has also taken an altogether different meaning. The area where one needs to use all the resources at disposal to compute the results efficiently and quickly is known as HPC (High Performance Computing). Evolution of computers has given the idea of using the entire RAM at disposal while computing the results; hence, parallelization becomes highly desirable. The goal of this project is to parallelize distributed memory systems using WINDOWS platform, analyzing some small(computationally) parallelized problems and if possible then trying to implement them for the software ABAQUS(FEM tool). Moreover the parallel program developed can be used for numerical solution to Helmholtz equation. The basic equation governing acoustics is the Helmholtz equation; analytical complications have driven researchers to develop Numerical methods to solve this equation. Numerical methods in turn have posed computational difficulties even with the use of modern day computers, parallelization of solution of Helmholtz equation is the result of these problems. The standard algorithms are available for the Numerical methods and they only need to be programmed on a platform which can support parallel programming. By the implementation of suitable parallel techniques a considerable amount of efficiency with respect to time in obtaining the solutions can be achieved. 2008-11-05T10:31:22Z http://hdl.handle.net/2262/11019 Title: The Engineering Investigation of the Water Flow past the Butterfly Valve Author: Chaiworapuek, Weerachai Abstract: This paper presents a numerical simulation of flow past the butterfly valve in static and dynamic analysis using commercial fluid dynamics software FLUENT. In static analysis, the positions of the disk were set to be 0 ( completely opened ), 30, 45, 60 and 75 degrees under 1, 2 and 3 m/s water speed. The values of angular velocity were set to be 0.039 and 1.57 rad/s under 1 m/s water speed in dynamic analysis. The study focuses on the investigation of the characteristic of loss coefficient and torque behavior of the 150 mm and 300 mm butterfly valve. From the results obtained, it was found that the loss coefficient and torque values increased when the disk angle was increased. By increasing the water speed, the loss coefficient remained constant while torque value increased. In dynamic analysis of both angular speeds, the maximum torque occurred around 70-80 in closing turn and 100-110 in opening turn. The experiment was also carried out to verify the numerical results. By comparing between the experimental and numerical method, it was found that the loss coefficient and torque value could be determined responsibly. The acceptable comparisons were seen. 2007-01-01T00:00:00Z http://hdl.handle.net/2262/11018 Title: Analysis of the Potential of DynaFlexPro as a Modeling Software by its Application in the Roll Stability of Heavy-Duty Elliptical Tankers using Trammel Pendulum to Simulate Fluid Sloshing Author: Goru, Venu Gopal Abstract: One of the most common ways for commercial vehicles to loose their stability is by rollover. Partially filled heavy-duty tankers manoeuvring constant radius turns or lane change maneuvers have lower rollover threshold than other vehicles because of the high center of gravity and dynamic sloshing of the liquid payload. A number of analytical and numerical methods have been used till date to study the motion of fluid in a container and its effect on the container. One of the simplest and most effective ways is by modeling the fluid as a pendulum. Depending on the shape and size of the container, different types of pendulums have been proposed. In this case as the study was based on elliptical cisterns, a trammel pendulum was chosen and the fundamental basis of selecting the appropriate pendulum parameters has been obtained by studies performed by Salem [12]. One of the main aspects of this project is the utilization of completely new multibody computer-aided engineering (MCAE) software packages called DynaFlexPro (DFP) and DynaFlexPro/Tire released in 2005 by MotionPro, Inc and marketed by MapleSoft Inc. These new commercial packages of Maple were chosen to model the Trammel pendulum and the Tractor and articulated Tanker vehicle. Firstly a model of a trammel pendulum was created and it’s kinematic and dynamic effects were studied. The fundamental basis of selecting the appropriate pendulum parameters have been obtained by matching the pendulum dynamic effects with fluid sloshing dynamic effects obtained by using Finite Element (FE) fluid models in the work of Salem. Once a working model was achieved, a 2-D Tanker model was made and the Trammel pendulum model was integrated to study the effect of sloshing on the roll stability of heavy duty tankers. The rollover threshold of 2-D models ranged from 0.9g to 0.25g because of which more realistic 3-D models of Tractor and Tanker were made. Due to some problems in the assembly of Tractor and Tanker, the 3-D Tanker was modified and basic tests were simulated. The 3-D Tanker model predicted critical fill levels that agree with the values reported in the literature based on much more complex and time consuming experimental and analytical methods proving the efficiency of the modeling software. In addition sloshing effects were clearly visible from the results validating the trammel pendulum as a simple and efficient way of modeling sloshing of fluids in elliptical tankers. 2007-01-01T00:00:00Z http://hdl.handle.net/2262/11020 Title: Analysis of the rough contact in axisymmetric upsetting Author: Cui, Yu Abstract: Characterization of surface roughness is important in the frictional behavior of two contact surfaces. In general, it has been found that friction increases with average roughness. The prediction of friction and stress/ strain/ deformation is of interest in the friction-sensitive process such as aximmetric upsetting. However, the classical friction laws, such as Coulomb's law and its extension - Coulomb-Amonton's law, Coulomb-Orowan are found to be coarse and oversimplified especially in the presence of surface complexities. The first objective of this project is to examine the microscopic evolution of the upsetting process with Finite Element software, with the focus on the interaction between the tool asperity and the plastic wave. The second objective is to evaluate Coulomb’s law and Plastic wave theory based on small-scale numerical models. The third objective is to implant the friction laws and prior findings into the experiment-size Finite Element models so that comparison between simulation and expriments could be made. This project is a contribution to the definition of a new friction test for bulk forming processes. 2007-01-01T00:00:00Z http://hdl.handle.net/2262/11021 Title: Acoustic particle velocity measurement by ultra-light membrane and its applications in acoustic holography Author: ZHOU, ZE Abstract: Acoustic holography is a non-destructive method used to determine the spatial propagation of acoustical waves. Conventionally, the acoustic holography measures the acoustic pressure. Until recently, a very limited number of techniques to measure the acoustic particle velocity have been introduced. The Laboratory of Vibration and Acoustics of INSA de Lyon, France has recently developed a novel method to directly measure the acoustic velocity field by a light membrane, with the assistance of a laser vibrometer. Theories allowing getting acoustic pressure and acoustic power from particle velocity have also been developed. The primary goal of this project is to apply the recently developed theories to a series of acoustic measurements. The objectives consist of the validation of the method and the evaluation of its performances under various circumstances. In several experiments, results obtained by the approach of membrane’s measurement are compared with results from conventional microphone’s measurement and a relatively new P-U probe measurement. 2007-01-01T00:00:00Z http://hdl.handle.net/2262/11022 Title: The Use of CFD for Investigating Fluidelastic Instability in Tube Arrays Author: Sanches, Rafael Adriano Kuche Abstract: There are several applications of tube arrays subject to cross flow in the industry, mostly for heat exchanging. These tubes are subject to forces arising due to the flow, and under certain conditions they can experience large amplitude self exited vibration, phenomenon named Fluidelastic Instability (FEI), a potentially catastrophic phenomenon when occurring in structures dimensioned for static loads. Through this work a brief review of the different methods of modelling FEI is presented, and the use of the commercial Computational Fluid Dynamics (CFD) solver FLUENT to predict the forces acting in a tube of an array subject to cross flow is analyzed. A few experiments are performed in order to compare the simulation results to real data. Finally, the Reynolds Stress Model (RSM) is found to provide better results, but still not very faithful to the reality. Guidelines for preparation of a good simulation of flow through a tube array, mesh construction and turbulent models are presented. A comparison between results from several turbulent models is presented. The most appropriate model is then chosen and more results are presented. Future work is pointed to simulation with dynamic mesh and to a methodology of adaptation of CFD results for quasi steady fluidelastic instability model. 2007-01-01T00:00:00Z