A Zonal Approach to the Design of Finite Element Grids for 3-D Transonic Flows with Complex Geometries.

1985 ◽  
Author(s):  
Akin Ecer
Keyword(s):  
Finite Element ◽  
Complex Geometries ◽  
Transonic Flows

LOW AND HIGH ORDER FINITE ELEMENT METHOD: EXPERIENCE IN SEISMIC MODELING

1994 ◽  
Vol 02 (04) ◽  
pp. 371-422 ◽  
Author(s):  
E. PADOVANI ◽  
E. PRIOLO ◽  
G. SERIANI
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Computational Efficiency ◽  
High Order ◽  
Cholesky Factorization ◽  
Complex Geometries ◽  
Spectral Elements ◽  
Seismic Modeling ◽  
Static Condensation ◽  
Element Method

The finite element method (FEM) is a numerical technique well suited to solving problems of elastic wave propagation in complex geometries and heterogeneous media. The main advantages are that very irregular grids can be used, free surface boundary conditions can be easily taken into account, a good reconstruction is possible of irregular surface topography, and complex geometries, such as curved, dipping and rough interfaces, intrusions, cusps, and holes can be defined. The main drawbacks of the classical approach are the need for a large amount of memory, low computational efficiency, and the possible appearance of spurious effects. In this paper we describe some experience in improving the computational efficiency of a finite element code based on a global approach, and used for seismic modeling in geophysical oil exploration. Results from the use of different methods and models run on a mini-superworkstation APOLLO DN10000 are reported and compared. With Chebyshev spectral elements, great accuracy can be reached with almost no numerical artifacts. Static condensation of the spectral element's internal nodes dramatically reduces memory requirements and CPU time. Time integration performed with the classical implicit Newmark scheme is very accurate but not very efficient. Due to the high sparsity of the matrices, the use of compressed storage is shown to greatly reduce not only memory requirements but also computing time. The operation which most affects the performance is the matrix-by-vector product; an effective programming of this subroutine for the storage technique used is decisive. The conjugate gradient method preconditioned by incomplete Cholesky factorization provides, in general, a good compromise between efficiency and memory requirements. Spectral elements greatly increase its efficiency, since the number of iterations is reduced. The most efficient and accurate method is a hybrid iterative-direct solution of the linear system arising from the static condensation of high order elements. The size of 2D models that can be handled in a reasonable time on this kind of computer is nowadays hardly sufficient, and significant 3D modeling is completely unfeasible. However the introduction of new FEM algorithms coupled with the use of new computer architectures is encouraging for the future.

Solidification Heat Transfer and Base Separation Analysis in the Casting of an Energetic Material in a Projectile

2005 ◽  
Author(s):  
Dawei Sun ◽  
S. Ravi Annapragada ◽  
Suresh V. Garimella ◽  
Sanjeev Sing
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Numerical Model ◽  
Residual Stresses ◽  
Energetic Materials ◽  
Energetic Material ◽  
Complex Geometries ◽  
Experimental Measurements ◽  
Linear Temperature ◽  
High Prandtl Number

This paper investigates the problem of base separation in the casting of energetic materials in a projectile. Special challenges that arise in casting high Prandtl number energetic materials in projectiles of complex geometries are addressed. A comprehensive numerical model is developed by integrating finite volume and finite element methods to analyze the thermal and flow fields as well as the residual stresses. The predictions, which are confirmed by experimental measurements, suggest that sustenance of a linear temperature profile along the projectile axis can eliminate base separation, and also reduce residual stresses in the final casting.

Automated Finite Element Analysis on Tree Branches

2016 ◽  
Author(s):  
Devon Keane ◽  
Domenick Avanzi ◽  
Lance Evans ◽  
Zahra Shahbazi
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
User Interface ◽  
Elemental Analysis ◽  
Biological Systems ◽  
Complex Geometries ◽  
Analysis Software ◽  
Element Analysis

There are many instances where creating finite element analysis (FEA) requires extensive time and effort. Such instances include finite element analysis of tree branches with complex geometries and varying mechanical properties. In this paper, we discuss the development of Immediate-TREE, a program and its associated Guided User Interface (GUI) that provides researchers a fast and efficient finite elemental analysis of tree branches. This process was discussed in which finite element analysis were automated with the use of computer generated Python files. Immediate-TREE uses tree branch’s data (geometry, mechanical properties and etc.) provided through experiment and generates Python files, which were then run in finite element analysis software (Abaqus) to complete the analysis. Immediate-TREE is approximately 240 times faster than creating the model directly in the FEA software (Abaqus). The process used to develop Immediate-TREE can be applied to other finite element analysis of biological systems such as bone and tooth.

Finite Element Modeling for the Locomotive Traction Gears

2014 ◽  
Vol 889-890 ◽  
pp. 3-8 ◽  
Author(s):  
Xiao Chun Shi ◽  
Wei Dong He ◽  
Jun Hua Bao
Keyword(s):  
Finite Element ◽  
Parametric Design ◽  
Gear Tooth ◽  
Element Model ◽  
Strength Analysis ◽  
Complex Geometries ◽  
Solid Foundation ◽  
Transition Curves ◽  
The Finite Element Model ◽  
Ansys Parametric Design Language

In order to improve the bearing capacity and service life of the locomotive traction gears, modern design methods are used to optimize the gear tooth curves and their parameters. The simulation of the involute tooth curves and tooth root transition curves of the traction gears are build by Ansys Parametric Design Language (APDL). It can accurately describe the finite element model with complex geometries. It laid a solid foundation for the tooth strength analysis and modification.

scholarly journals Finite Element Analysis of Turbulent Flows Using LES and Dynamic Subgrid-Scale Models in Complex Geometries

2011 ◽  
Vol 2011 ◽  
pp. 1-20 ◽  
Author(s):  
Wang Wenquan ◽  
Zhang Lixiang ◽  
Yan Yan ◽  
Guo Yakun
Keyword(s):  
Finite Element ◽  
Turbulent Flow ◽  
Turbulent Flows ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Turbulent Channel Flow ◽  
Francis Turbine ◽  
Complex Geometries ◽  
Subgrid Scale ◽  
Element Analysis

An innovative computational model is presented for the large eddy simulation (LES) of multidimensional unsteady turbulent flow problems in complex geometries. The main objectives of this research are to know more about the structure of turbulent flows, to identify their three-dimensional characteristic, and to study physical effects due to complex fluid flow. The filtered Navier-Stokes equations are used to simulate large scales; however, they are supplemented by dynamic subgrid-scale (DSGS) models to simulate the energy transfer from large scales toward subgrid-scales, where this energy will be dissipated by molecular viscosity. Based on the Taylor-Galerkin schemes for the convection-diffusion problems, this model is implemented in a three-dimensional finite element code using a three-step finite element method (FEM). Turbulent channel flow and flow over a backward-facing step are considered as a benchmark for validating the methodology by comparing with the direct numerical simulation (DNS) results or experimental data. Also, qualitative and quantitative aspects of three-dimensional complex turbulent flow in a strong 3D blade passage of a Francis turbine are analyzed.

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