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in subjects: "Mesh Generation"

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Methods for Multisweep Automation

Sweeping has become the workhorse algorithm for creating conforming hexahedral meshes of complex models. This paper describes progress on the automatic, robust generation of MultiSwept meshes in CUBIT. MultiSweeping extends the class of volumes that may be swept to include those with multiple source and multiple target surfaces. While not yet perfect, CUBIT's MultiSweeping has recently become more reliable, and been extended to assemblies of volumes. Sweep Forging automates the process of makin… more

Date: September 14, 2000

Creator: Shepherd, Jason F.; Mitchell, Scott A.; Knupp, Patrick & White, David R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Algebraic mesh quality metrics

Quality metrics for structured and unstructured mesh generation are placed within an algebraic framework to form a mathematical theory of mesh quality metrics. The theory, based on the Jacobian and related matrices, provides a means of constructing, classifying, and evaluating mesh quality metrics. The Jacobian matrix is factored into geometrically meaningful parts. A nodally-invariant Jacobian matrix can be defined for simplicial elements using a weight matrix derived from the Jacobian matrix … more

Date: April 24, 2000

Creator: Knupp, Patrick

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Pamgen, a library for parallel generation of simple finite element meshes.

Generating finite-element meshes is a serious bottleneck for large parallel simulations. When mesh generation is limited to serial machines and element counts approach a billion, this bottleneck becomes a roadblock. Pamgen is a parallel mesh generation library that allows on-the-fly scalable generation of hexahedral and quadrilateral finite element meshes for several simple geometries. It has been used to generate more that 1.1 billion elements on 17,576 processors. Pamgen generates an unstruct… more

Date: April 1, 2008

Creator: Foucar, James G.; Drake, Richard Roy; Hensinger, David M. & Gardiner, Thomas Anthony

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

The generation of hexahedral meshes for assembly geometries: A survey

The finite element method is being used today to model component assemblies in a wide variety of application areas, including structural mechanics, fluid simulations, and others. Generating hexahedral meshes for these assemblies usually requires the use of geometry decomposition, with different meshing algorithms applied to different regions. While the primary motivation for this approach remains the lack of an automatic, reliable all-hexahedral meshing algorithm, requirements in mesh quality a… more

Date: February 14, 2000

Creator: TAUTGES,TIMOTHY J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

High-Fidelity Geometric Modelling for Biomedical Applications

We describe a combination of algorithms for high fidelity geometric modeling and mesh generation. Although our methods and implementations are application-neutral, our primary target application is multiscale biomedical models that range in scales across the molecular, cellular, and organ levels. Our software toolchain implementing these algorithms is general in the sense that it can take as input a molecule in PDB/PQR forms, a 3D scalar volume, or a user-defined triangular surface mesh that ma… more

Date: April 1, 2008

Creator: Zeyun Yu, Michael Holst, and J.A. McCammon

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A Method for Controlling Skew on Linked Surfaces

A new method for lessening skew in mapped meshes is presented. This new method involves progressive subdivision of a surface into loops consisting of four sides. Using these loops, constraints can then be set on the curves of the surface, which will propagate interval assignments across the surface, allowing a mesh with a better skew metric to be generated.

Date: September 27, 1999

Creator: BENZLEY,STEVEN E.; KERR,ROBERT A.; MITCHELL,SCOTT A. & WHITE,DAVID R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Adaptive anisotropic meshing for steady convection-dominated problems

Obtaining accurate solutions for convection–diffusion equations is challenging due to the presence of layers when convection dominates the diffusion. To solve this problem, we design an adaptive meshing algorithm which optimizes the alignment of anisotropic meshes with the numerical solution. Three main ingredients are used. First, the streamline upwind Petrov–Galerkin method is used to produce a stabilized solution. Second, an adapted metric tensor is computed from the approximate solution. Th… more

Date: January 1, 2009

Creator: Nguyen, Hoa; Gunzburger, Max; Ju, Lili & Burkardt, John

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The Graft Tool: An All-Hexahedral Transition Algorithm for Creating a Multi-Directional Swept Volume Mesh

Sweeping algorithms have become very mature and can create a semi-structured mesh on a large set of solids. However, these algorithms require that all linking surfaces be mappable or submappable. This restriction excludes solids with imprints or protrusions on the linking surfaces. The grafting algorithm allows these solids to be swept. It then locally modifies the position and connectivity of the nodes on the linking surfaces to align with the graft surfaces. Once a high-quality surface mesh i… more

Date: September 27, 1999

Creator: BENZLEY,STEVEN E.; JANKOVICH,STEVEN R.; MITCHELL,SCOTT A. & SHEPHERD,JASON F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

An improved bi-level algorithm for partitioning dynamic grid hierarchies.

Structured adaptive mesh refinement methods are being widely used for computer simulations of various physical phenomena. Parallel implementations potentially offer realistic simulations of complex three-dimensional applications. But achieving good scalability for large-scale applications is non-trivial. Performance is limited by the partitioner's ability to efficiently use the underlying parallel computer's resources. Designed on sound SAMR principles, Nature+Fable is a hybrid, dedicated SAMR … more

Date: May 1, 2006

Creator: Deiterding, Ralf; Johansson, Henrik; Steensland, Johan & Ray, Jaideep

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Adaptive mesh refinement for time-domain electromagnetics using vector finite elements :a feasibility study.

This report investigates the feasibility of applying Adaptive Mesh Refinement (AMR) techniques to a vector finite element formulation for the wave equation in three dimensions. Possible error estimators are considered first. Next, approaches for refining tetrahedral elements are reviewed. AMR capabilities within the Nevada framework are then evaluated. We summarize our conclusions on the feasibility of AMR for time-domain vector finite elements and identify a path forward.

Date: December 1, 2005

Creator: Turner, C. David; Kotulski, Joseph Daniel & Pasik, Michael Francis

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Using high-order methods on adaptively refined block-structured meshes - discretizations, interpolations, and filters.

Block-structured adaptively refined meshes (SAMR) strive for efficient resolution of partial differential equations (PDEs) solved on large computational domains by clustering mesh points only where required by large gradients. Previous work has indicated that fourth-order convergence can be achieved on such meshes by using a suitable combination of high-order discretizations, interpolations, and filters and can deliver significant computational savings over conventional second-order methods at … more

Date: January 1, 2006

Creator: Ray, Jaideep; Lefantzi, Sophia; Najm, Habib N. & Kennedy, Christopher A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Visualization Tools for Adaptive Mesh Refinement Data

Adaptive Mesh Refinement (AMR) is a highly effective method for simulations that span a large range of spatiotemporal scales, such as astrophysical simulations that must accommodate ranges from interstellar to sub-planetary. Most mainstream visualization tools still lack support for AMR as a first class data type and AMR code teams use custom built applications for AMR visualization. The Department of Energy's (DOE's) Science Discovery through Advanced Computing (SciDAC) Visualization and Analy… more

Date: May 9, 2007

Creator: Weber, Gunther H.; Beckner, Vincent E.; Childs, Hank; Ligocki,Terry J.; Miller, Mark C.; Van Straalen, Brian et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Volume Decomposition and Feature Recognition for Hexahedral Mesh Generation

Considerable progress has been made on automatic hexahedral mesh generation in recent years. Several automatic meshing algorithms have proven to be very reliable on certain classes of geometry. While it is always worth pursuing general algorithms viable on more general geometry, a combination of the well-established algorithms is ready to take on classes of complicated geometry. By partitioning the entire geometry into meshable pieces matched with appropriate meshing algorithm the original geom… more

Date: September 27, 1999

Creator: Gadh, Rajit; Lu, Yong & Tautges, Timothy J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Hexahedron Projection for Curvilinear Grids

This paper presents a method of dividing into triangle fans the most common projections of hexahedra from curvilinear meshes, so that they can be volume rendered in hardware, with a fragment program for 32-bit floating point compositing.

Date: June 13, 2006

Creator: Max, N.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Curved mesh generation and mesh refinement using Lagrangian solid mechanics

We propose a method for generating well-shaped curved unstructured meshes using a nonlinear elasticity analogy. The geometry of the domain to be meshed is represented as an elastic solid. The undeformed geometry is the initial mesh of linear triangular or tetrahedral elements. The external loading results from prescribing a boundary displacement to be that of the curved geometry, and the final configuration is determined by solving for the equilibrium configuration. The deformations are represe… more

Date: December 31, 2008

Creator: Persson, P.-O. & Peraire, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

An Improved Linear Tetrahedral Element for Plasticity

A stabilized, nodally integrated linear tetrahedral is formulated and analyzed. It is well known that linear tetrahedral elements perform poorly in problems with plasticity, nearly incompressible materials, and acute bending. For a variety of reasons, linear tetrahedral elements are preferable to quadratic tetrahedral elements in most nonlinear problems. Whereas, mixed methods work well for linear hexahedral elements, they don't for linear tetrahedrals. On the other hand, automatic mesh generat… more

Date: April 25, 2005

Creator: Puso, M

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Unstructured Mesh Connectivity in Unstructured Mapping

The connectivity interface for UnstructuredMapping has been rewritten to provide a more thorough interface to the mesh. This new design also resembles the TSTT mesh query interface. While data is still stored in array form, indexed by integers, the interface provides iterators through the mesh entities and adjacencies. This document describes the additions to the UnstructuredMapping class as well as the definition and use of the UnstructuredMappingIterator and UnstructuredMappingAdjacencyIterat… more

Date: October 22, 2002

Creator: Chand, K

Item Type: Text

Partner: UNT Libraries Government Documents Department

open access

A computational study of nodal-based tetrahedral element behavior.

This report explores the behavior of nodal-based tetrahedral elements on six sample problems, and compares their solution to that of a corresponding hexahedral mesh. The problems demonstrate that while certain aspects of the solution field for the nodal-based tetrahedrons provide good quality results, the pressure field tends to be of poor quality. Results appear to be strongly affected by the connectivity of the tetrahedral elements. Simulations that rely on the pressure field, such as those w… more

Date: September 1, 2010

Creator: Gullerud, Arne S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Verification of the W76-1 hostile environments model

Demonstrating mesh convergence for a finite element analysis requires multiple meshes, but creating high quality meshes is a time-consuming task. Furthermore, estimates of the amount of error caused by mesh refinement are difficult to make for a sequence of unrelated, unstructured finite element meshes. A solution for both of these problems is to automatically generate a refined mesh by subdividing every element in the original mesh. The resulting refined mesh has a uniform 'mesh refinement rat… more

Date: January 1, 2002

Creator: Stevens, R. Robert

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Detecting Translation Errors in CAD Surfaces and Preparing Geometries for Mesh Generation

The authors have developed tools for the efficient preparation of CAD geometries for mesh generation. Geometries are read from IGES files and then maintained in a boundary-representation consisting of a patchwork of trimmed and untrimmed surfaces. Gross errors in the geometry can be identified and removed automatically while a user interface is provided for manipulating the geometry (such as correcting invalid trimming curves or removing unwanted details). Modifying the geometry by adding or de… more

Date: August 27, 2001

Creator: Petersson, N Anders & Chand, K K

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Creating Interoperable Meshing and Discretization Software: The Terascale Simulation Tools and Technology Center

We present an overview of the technical objectives of the Terascale Simulation Tools and Technologies center. The primary goal of this multi-institution collaboration is to develop technologies that enable application scientists to easily use multiple mesh and discretization strategies within a single simulation on terascale computers. The discussion focuses on our efforts to create interoperable mesh generation tools, high-order discretization techniques, and adaptive meshing strategies.

Date: March 28, 2002

Creator: Brown, D.; Freitag, L. & Glimm, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

New laser driver for physics modeling codes using unstructured 3d grids

We present a status report on the current state of development, testing and application of a new scheme for laser beam evolution and power deposition on three-dimensional unstructured grids. The scheme is being encapsulated in a C++ library for convenient porting to existing modeling codes. We have added a new ray propagator that is second order in time, allowing rays to refract within computational zones as well as at zone interfaces. In a globally constant free-electron density gradient on a … more

Date: February 1, 1999

Creator: Kaiser, T; Milovich, J L; Prasad, M K & Shestakov, A I

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The Factory Approach to Creating TSTT Meshes

The factory approach (a.k.a. virtual constructor) hides the details of the class implementing the TSTT from TSTT users. In version 0.5 of TSTT.sidl, the client hard codes the name of the implementing class into their code. The client is forced to choose from the small set of possible concrete classes defined in TSTT.sidl. This approach makes it impossible to support multiple implementations of the TSTT in a single process because each implementation has to implement the same class. The factory … more

Date: October 21, 2003

Creator: Epperly, T

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Scalable Dynamic Mesh Algorithms and Software. Final Report

This report details results from work conducted under the grant entitled ''Scalable Dynamic Mesh Algorithms and Software'' for the period September 1, 1998 to November 30, 2001.

Date: March 15, 2002

Creator: Jones, Mark T. & Plassmann, Paul E.

Item Type: Report

Partner: UNT Libraries Government Documents Department