Spelling suggestions: "subject:"refreshing"" "subject:"meshing""
1 |
Comparison of Two Vortex-in-cell Schemes Implemented to a Three-dimensional Temporal Mixing LayerSadek, Nabel 24 August 2012 (has links)
Numerical simulations are presented for three dimensional viscous incompressible free shear flows. The numerical method is based on solving the vorticity equation using Vortex-In-Cell method. In this method, the vorticity field is discretized into a finite set of Lagrangian elements (particles) and the computational domain is covered by Eulerian mesh. Velocity field is computed on the mesh by solving Poisson equation. The solution proceeds in time by advecting the particles with the flow. Second order Adam-Bashford method is used for time integration. Exchange of information between Lagrangian particles and Eulerian grid is carried out using the M’4 interpolation scheme. The classical inviscid scheme is enhanced to account for stretching and viscous effects. For that matter, two schemes are used. The first one used periodic remeshing of the vortex particles along with fourth order finite difference approximation for the partial derivatives of the stretching and viscous terms. In the second scheme, derivatives are approximated by least squares polynomial. The novelty of this work is signified by using the moving least squares technique within the framework of the Vortex-in-Cell method and implementing it to a three dimensional temporal mixing layer. Comparisons of the mean flow and velocity statistics are made with experimental studies. The results confirm the validity of the present schemes. Both schemes also demonstrate capability to qualitatively capture significant flow scales, and allow gaining physical insight as to the development of instabilities and the formation of three dimensional vortex structures. The two schemes show acceptable low numerical diffusion as well.
|
2 |
Numerical Prediction of Panel Dent Resistance Incorporating Panel Forming StrainsThomas, Dylan January 2001 (has links)
This thesis presents a numerical method of predicting both static and dynamic denting phenomena in automotive body panels. The finite element method is used as a predictive tool to assess panel performance prior to production of tooling. A custom software package has been developed to transform existing finite element forming models into ready-to-run finite element denting models, minimising the effort required to perform dent simulations. Over 50 multi-step finite element models were performed. Each of these models simulated the forming, springback and subsequent denting of either 1. 05mm thick AA5754, or0. 81mm, 0. 93mm or 1. 00mm thick AA6111 aluminum sheet. Experimental validation of dent predictions using this method has shown that the trends in both static and dynamic dent resistance have been captured quite well. These validation studies demonstrated the sensitivity of the results to various parameters such as panel thickness, pre-strain, curvature and thickness, as well as numerical formulation parameters. It has been determined that it is particularly important to use forming data within the denting models for accurate results to be obtained.
|
3 |
Comparison of Two Vortex-in-cell Schemes Implemented to a Three-dimensional Temporal Mixing LayerSadek, Nabel 24 August 2012 (has links)
Numerical simulations are presented for three dimensional viscous incompressible free shear flows. The numerical method is based on solving the vorticity equation using Vortex-In-Cell method. In this method, the vorticity field is discretized into a finite set of Lagrangian elements (particles) and the computational domain is covered by Eulerian mesh. Velocity field is computed on the mesh by solving Poisson equation. The solution proceeds in time by advecting the particles with the flow. Second order Adam-Bashford method is used for time integration. Exchange of information between Lagrangian particles and Eulerian grid is carried out using the M’4 interpolation scheme. The classical inviscid scheme is enhanced to account for stretching and viscous effects. For that matter, two schemes are used. The first one used periodic remeshing of the vortex particles along with fourth order finite difference approximation for the partial derivatives of the stretching and viscous terms. In the second scheme, derivatives are approximated by least squares polynomial. The novelty of this work is signified by using the moving least squares technique within the framework of the Vortex-in-Cell method and implementing it to a three dimensional temporal mixing layer. Comparisons of the mean flow and velocity statistics are made with experimental studies. The results confirm the validity of the present schemes. Both schemes also demonstrate capability to qualitatively capture significant flow scales, and allow gaining physical insight as to the development of instabilities and the formation of three dimensional vortex structures. The two schemes show acceptable low numerical diffusion as well.
|
4 |
Numerical Prediction of Panel Dent Resistance Incorporating Panel Forming StrainsThomas, Dylan January 2001 (has links)
This thesis presents a numerical method of predicting both static and dynamic denting phenomena in automotive body panels. The finite element method is used as a predictive tool to assess panel performance prior to production of tooling. A custom software package has been developed to transform existing finite element forming models into ready-to-run finite element denting models, minimising the effort required to perform dent simulations. Over 50 multi-step finite element models were performed. Each of these models simulated the forming, springback and subsequent denting of either 1. 05mm thick AA5754, or0. 81mm, 0. 93mm or 1. 00mm thick AA6111 aluminum sheet. Experimental validation of dent predictions using this method has shown that the trends in both static and dynamic dent resistance have been captured quite well. These validation studies demonstrated the sensitivity of the results to various parameters such as panel thickness, pre-strain, curvature and thickness, as well as numerical formulation parameters. It has been determined that it is particularly important to use forming data within the denting models for accurate results to be obtained.
|
5 |
Simulation Of Orthogonal Metal Cutting By Finite Element AnalysisBil, Halil 01 January 2003 (has links) (PDF)
The aim of this thesis is to compare various simulation models of orthogonal
cutting process with each other as well as with various experiments. The effects
of several process parameters, such as friction and separation criterion, on the
results are analyzed. As simulation tool, commercial implicit finite element codes
MSC.Marc, Deform2D and the explicit code Thirdwave AdvantEdge are used.
Separation of chip from the workpiece is achieved either only with continuous
remeshing or by erasing elements according to the damage accumulated. From
the results cutting and thrust forces, shear angle, chip thickness and contact length
between the chip and the rake face of the tool can be estimated. For verification
of results several cutting experiments are performed at different cutting
conditions, such as rake angle and feed rate. Results show that commercial codes
are able to simulate orthogonal cutting operations within reasonable limits.
Friction is found to be the most critical parameter in the simulation, since good
agreement can be achieved for individual process variables by tuning it.
Therefore, simulation results must be assessed with all process variables and
friction parameter should be tuned according to the shear angle results. Plain damage model seems not appropriate for separation purposes of machining
simulations. On the other hand, although remeshing gives good results, it leads to
the misconception of crack generation at the tip of the tool. Therefore, a new
separation criterion is necessary to achieve both good physical modeling and
prediction of process variables.
|
6 |
Comparison of Two Vortex-in-cell Schemes Implemented to a Three-dimensional Temporal Mixing LayerSadek, Nabel January 2012 (has links)
Numerical simulations are presented for three dimensional viscous incompressible free shear flows. The numerical method is based on solving the vorticity equation using Vortex-In-Cell method. In this method, the vorticity field is discretized into a finite set of Lagrangian elements (particles) and the computational domain is covered by Eulerian mesh. Velocity field is computed on the mesh by solving Poisson equation. The solution proceeds in time by advecting the particles with the flow. Second order Adam-Bashford method is used for time integration. Exchange of information between Lagrangian particles and Eulerian grid is carried out using the M’4 interpolation scheme. The classical inviscid scheme is enhanced to account for stretching and viscous effects. For that matter, two schemes are used. The first one used periodic remeshing of the vortex particles along with fourth order finite difference approximation for the partial derivatives of the stretching and viscous terms. In the second scheme, derivatives are approximated by least squares polynomial. The novelty of this work is signified by using the moving least squares technique within the framework of the Vortex-in-Cell method and implementing it to a three dimensional temporal mixing layer. Comparisons of the mean flow and velocity statistics are made with experimental studies. The results confirm the validity of the present schemes. Both schemes also demonstrate capability to qualitatively capture significant flow scales, and allow gaining physical insight as to the development of instabilities and the formation of three dimensional vortex structures. The two schemes show acceptable low numerical diffusion as well.
|
7 |
A finite element method for ring rolling processesDewasurendra, Lohitha January 1998 (has links)
No description available.
|
8 |
Images géométriques de genre arbitraire dans le domaine sphériqueGauthier, Mathieu January 2008 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.
|
9 |
A Comparative Study On Polygonal Mesh Simplification AlgorithmsYirci, Murat 01 September 2008 (has links) (PDF)
Polygonal meshes are a common way of representing 3D surface models in many
different areas of computer graphics and geometry processing. However, these
models are becoming more and more complex which increases the cost of processing
these models. In order to reduce this cost, mesh simplification algorithms are
developed. Another important property of a polygonal mesh model is that whether it
is regular or not. Regular meshes have many advantages over the irregular ones in
terms of memory requirements, efficient processing, rendering etc. In this thesis
work, both mesh simplification and regular remeshing algorithms are studied.
Moreover, some of the popular mesh libraries are compared with respect to their
approaches and performance to the mesh simplification. In addition, mesh models
with disk topology are remeshed and converted to regular ones.
|
10 |
Images géométriques de genre arbitraire dans le domaine sphériqueGauthier, Mathieu January 2008 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal
|
Page generated in 0.0787 seconds