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1993, International Journal for Numerical Methods in Engineering
A simple algorithm is developed for adaptive and automatic h refinement of two-dimensional triangular finite element meshes. The algorithm is based on an element refinement ratio that can be calculated from an a posteriori error indicator. The element subdivision algorithm is robust and recursive. Smooth transition between large and small elements is achieved without significant degradation of the aspect ratio of the elements in the mesh. Several example problems are presented to illustrate the utility of the approach.
33rd Structures, Structural Dynamics and Materials Conference, 1992
A simple algoritlinl for adaptive and automatic h refinement of t,hree dimensional tetrahedral finite element meshes is presented. The algorithm is based on an aposteriori error indicator that is calculated by the finite element solver. The elrment subdivision algorithm is robust and rccilrsive. Smooth transition between large and small c~l(~lnents is achieved without significant degradation of the aspect rat,io of t,he elements in the n~e s h. An cxaniplr is presented to illustrate the utility of the approach.
Indian Journal of Engineering and Materials Sciences, 1999
Among the acce pt ab le numerical methods. Finite Element Analysis stands as the most acceptable one for problems characterised by partial differential equations. However. in accuracy in Finite Element An alysis is• unavoidable since a co ntinuum with infinite degrees of freedo m is modelled into finite degrees of freed o m. In addition to the mesh generation tas k being tedious and e rror prone. the accuracy and cost of the analysis de pe nd directly o n size. shape and number of d e ments in the mes h. The procedure of refining the mesh automatic ally based on the error estimate and distribution of the e rror is known as "adap ti ve" mesh refineme nt. A si mplified method called " Divide and Conquer" rule based on "Fuzzy Logic" is used to refi ne th e mes h by using Ir, p and Irp versions. Aut o matic mes h generato r develo ped in thi s paper based on Fuzzy log ic is able to develop well shaped elements. The program for automati c mes h gene ration and subsequent mesh re linement is developed in "C' language and the analys is is carried o ut usi ng " ANSYS " I package. Automatic mesh ge ne ratio n i~ app li cd to problems suc h as dam, square pl ate with a ho le. thi ck sphe rical press ure vessel and a co rbel and e rror less than 5 % is ac hi eved in most of th e cases.
Applied Sciences, 2021
The adaptive mesh techniques applied to the Finite Element Method have continuously been an active research line. However, these techniques are usually applied to tetrahedra. Here, we use the triangular prismatic element as the discretization shape for a Finite Element Method code with adaptivity. The adaptive process consists of three steps: error estimation, marking, and refinement. We adapt techniques already applied for other shapes to the triangular prisms, showing the differences here in detail. We use five different marking strategies, comparing the results obtained with different parameters. We adapt these strategies to a conformation process necessary to avoid hanging nodes in the resulting mesh. We have also applied two special rules to ensure the quality of the refined mesh. We show the effect of these rules with the Method of Manufactured Solutions and numerical results to validate the implementation introduced.
Advances in Engineering Software, 2007
In this paper, attention is restricted to mesh adaptivity. Traditionally, the most common mesh adaptive strategies for linear problems are used to reach a prescribed accuracy. This goal is best met with an h-adaptive scheme in combination with an error estimator. In an industrial context, the aim of the mechanical simulations in engineering design is not only to obtain greatest quality but more often a compromise between the desired quality and the computation cost (CPU time, storage, software, competence, human cost, computer used). In this paper we propose the use of alternative mesh refinement with an h-adaptive procedure for 3D elastic problems. The alternative mesh refinement criteria allow to obtain the maximum of accuracy for a prescribed cost. These adaptive strategies are based on a technique of error in constitutive relation (the process could be used with other error estimators) and an efficient adaptive technique which automatically takes into account the steep gradient areas. This work proposes a 3D method of adaptivity with the latest version of the INRIA automatic mesh generator GAMHIC3D.
IEEE Transactions on Magnetics, 1992
In this paper two strategies trying to reduce the overall number of flnite element computations needed in an adaptive meshing algorithm are proposed. In the flrst one numerical values of the estimated local error are used both to select the elemenb to be refined and to decide in how many new elements each of them will be Subdivided. In the second strategy a solution approximation and ita local error on a mesh are estimated from a previous approximate solution. For both methods the required algorithms are presented and the obtained results are compared and discussed.
2005 IEEE Antennas and Propagation Society International Symposium, 2005
Two error indicators of the solution of an electromagnetic problem by Finite Element Method (FEM) and two local refinement algorithms for tetrahedral meshes are developed and combined to build up different self-adaptive (h-refinement) algorithms. 2"d order curl-conforming N6delec tetrahedral elements are used. The performance of the different methods is checked and compared by means of the electromagnetic analysis of resonant cavities.
CFD Open Series, 2022
In the adaptive mesh refinement technique we start with a base coarse grid. As the solution proceeds we identify the regions requiring more resolution by some parameter characterizing the solution, say the local truncation error. We superimpose finer sub grids only on these regions. Finer and finer sub grids are added recursively until either a given maximum level of refinement is reached or the local truncation error has dropped below the desired level. Thus in an adaptive mesh refinement computation grid spacing is fixed for the base grid only and is determined locally for the sub grids according to the requirements of the problem
Advances in Finite Element Procedures and Techniques, 1998
A significant amount of computational mechanics research effort in recent years has concentrated on automation of the finite element method. The goal is to achieve a finite element system to which the engineer need only specify the problem geometry, material properties and boundary conditions, together with an indicator of the desired level of accuracy. A finite element model of the problem is then formed, and automatically refined until the specified level of accuracy is achieved. One method of refinement is the h-hierarchical method, in which an initial element mesh is progressively subdivided. However, examples of this type of refinement available in the literature use only quadrilateral or only triangular elements. This paper presents a scheme that allows elements with varying numbers of faces to be used together in an adaptive h-hierarchical analysis. The complexity that would normally be involved in such an approach is controlled by using object oriented techniques. Examples are presented illustrating the utility of the method.
2009
An h-adaptive unstructured mesh refinement strategy to solve unsteady problems by the finite element method is presented. The maximum level of refinement for the mesh is prescribed beforehand. The core operation of the strategy, namely the refinement of the elements, is described in detail. It is shown through numerical tests that one of the advantages of the chosen refinement procedure is to keep bounded the mesh quality. The type of element is not changed and no transition templates are used, therefore hanging nodes appear in the adapted mesh. The 1-irregular nodes refinement constraint is applied and the refinement process driven by this criterion is recursive. Both the strength and weakness of the adaptivity algorithm are mentioned, based on clock time measures and implementation issues. To show the proper working of the strategy, an axisymmetric, compressible non-viscous starting flow in a bell-shaped nozzle is solved over an unstructured mesh of hexahedra.
2006
This project produced algorithms for and software implementations of adaptive mesh refinement (AMR) methods for solving practical solid and thermal mechanics problems on multiprocessor parallel computers using unstructured finite element meshes. The overall goal is to provide computational solutions that are accurate to some prescribed tolerance, and adaptivity is the correct path toward this goal. These new tools will enable analysts to conduct more reliable simulations at reduced cost, both in terms of analyst and computer time. Previous academic research in the field of adaptive mesh refinement has produced a voluminous literature focused on error estimators and demonstration problems; relatively little progress has been made on producing efficient implementations suitable for large-scale problem solving on state-of-the-art computer systems. Research issues that were considered include: effective error estimators for nonlinear structural mechanics; local meshing at irregular geometric boundaries; and constructing efficient software for parallel computing environments.
Finite element analysts and designers need to feel confident in the results of their analyses before sending a product to prototype or production. Mesh discretization can greatly influence the desired results. In this paper we present framework for adaptive mesh refinement to obtain FEA results with a desired accuracy. The process involves adaptively refining the mesh based on solution error norms until the result desired converges to certain accuracy. The adaptive refinement/meshing process must be fully automatic and very robust. We present an exhaustive method to create a fully automatic and integrated process that takes advantage of many of the mesh refinement and mesh optimization algorithms found in literature. The results of the process provide the user with the desired accuracy in the smallest number of iterations possible.
IEEE Transactions on Magnetics, 1990
In this paper a comparative evaluation of performance of adaptive meshing algorithms with different error estimators is presented. The performance of a selected set of algorithms, based on an element-by-element h-refinement technique, are assessed in some test cases in comparison with analytical results, in a uniform environment. Finally, the features of various possible refinement indicators, adaption convergence criteria and error estimation parameters a r e presented and discussed.
IEEE Transactions on Magnetics, 1993
3-D Adaptive mesh refinement seems to be the answer towards full automation in the analysis of electromagnetic devices. The computational burden of 3-D problems can be reduced since with an efficient error estimator, optimal tetrahedral meshes are produced and the computational cost is minimized Further, the process of mesh generation, a headache for a finite element analyst, is completely automatic, requiring no user intervention. So self-adaptive mesh generation is proved to be an indispensable tool in 3-dimensional finite element analysis. In this paper 3 different criteria for error estimation are presented that are able to estimate the error present in the approximation model and the strategy followed in their implementation is analyzed Application to a test problem shows the effectiveness of the self-adaptive mesh generation algorithm
19th AIAA Applied Aerodynamics Conference, 2001
This paper describes and demonstrates a process for adaptive refinement of quadrilateral curved shell meshes using error estimates from MSC.Nastran ® . The meshes have been generated originally using Unigraphics'(UG) Scenario application.
Lecture Notes in Computer Science, 1998
International Journal for Numerical Methods in Fluids, 2006
New a posteriori error indicators based on edgewise slope-limiting are presented. The L2-norm is employed to measure the error of the solution gradient in both global and element sense. A second-order Newton–Cotes formula is utilized in order to decompose the local gradient error from a 1 finite element solution into a sum of edge contributions. The slope values at edge midpoints are interpolated from the two adjacent vertices. Traditional techniques to recover (superconvergent) nodal gradient values from consistent finite element slopes are reviewed. The deficiencies of standard smoothing procedures—L2-projection and the Zienkiewicz–Zhu patch recovery—as applied to nonsmooth solutions are illustrated for simple academic configurations. The recovered gradient values are corrected by applying a slope limiter edge-by-edge so as to satisfy geometric constraints. The direct computation of slopes at edge midpoints by means of limited averaging of adjacent gradient values is proposed as an inexpensive alternative. Numerical tests for various solution profiles in one and two space dimensions are presented to demonstrate the potential of this postprocessing procedure as an error indicator. Finally, it is used to perform adaptive mesh refinement for compressible inviscid flow simulations. Copyright © 2006 John Wiley & Sons, Ltd.
IEEE Transactions on Magnetics, 1990
A sensitivity analysis has been used to determine the energy perturbation of the nodal position in a finite-element mesh. The sensitivity of the nodal position gives the refinement indication and can therefore be used in the adaptive procedure. This method provides an alternative approach to adaptive mesh generation and is illustrated by numerical examples
IEEE Transactions on Magnetics, 1988
In this paper five methods for local error estimation in a finite element solution for adaptive meshing are analyzed. All these methods are "a posteriori", single solution, element by element error estimators.
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