Keynote and Invited Speakers
Chuck Grindstaff serves as Vice President of Products (R&D) and Operations at UGS, Inc. Chuck has over 20 years of direct experience building and utilizing CAD/CAM/CAE/PDM systems for mechanical product design and manufacturing. During his experience at UGS, Inc. he has led the development of Unigraphics' geometric modeling capabilities, engineering applications, NC Machining and core system architecture and tools. He has been instrumental in establishing several key strategic relationships between UGS and its technology partners. Chuck has broad experience in delivery of high-technology automation systems. In addition to his contributions at UGS, he founded and let Cybermation, Inc. (later merged with Waveframe Corporation) producing state-of-the-art, high-end, signal processing systems for the entertainment industry. Chuck holds a Bachelor degree from Pomona College (Chemistry).
Department of Mechanical and Aerospace Engineering
Tim Baker received his bachelor's degree, master's degree and PhD in Mathematics from Cambridge University in the U.K. He has been active in CFD research for more than 25 years and has witnessed its evolution from methods for solving the small disturbance equation in two dimensions to fully fledged computations of the Euler and Navier Stokes equations for the flow around complex geometries.
His early work at the Aircraft Research Association in Bedford, England was in the development of flow algorithms for the compressible potential equation. During the last 18 years, he has been at Princeton University where he became involved in mesh generation. His meshing research has included both structured mesh generation as well as the development of unstructured meshing methods.
His current research interests include theoretical analysis of mesh quality and its influence on the accuracy of a finite element solution, development of algorithms for adaptive modification of time evolving tetrahedral meshes, and novel techniques for the approximation and manipulation of surfaces by triangulations.
Numerous computational simulations involve a physical domain whose shape is evolving with time. Familiar examples in which different domain boundaries remain fixed in shape while undergoing relative motion arise in store separation problems as well as the simulation of flow through pumps, jet engines and around pistons. Examples in which the domain boundary also undergoes deformation occur in aeroelasticity, crash simulation, metal forging and crack nucleation. All are characterized by computational domains that change substantially in shape.
Mesh modification for time evolving domains can be carried out by a three stage combination of mesh movement, mesh coarsening and mesh enrichment. One application of this three stage procedure forms one cycle of dynamic adaptation. The extent of domain deformation that can be accommodated during one cycle depends on how far the r-refinement stage can stretch the cells without creating an invalid mesh with negative cell volumes. Mesh coarsening based on edge collapse is then carried out to remove points associated with cells that have become badly shaped during the r-refinement stage. Finally, mesh enrichment serves to re-create a mesh whose cell quality is comparable to that of the original mesh. At each stage one is operating on a valid (i.e. conforming, space filling and non-overlapping) mesh which thus avoids the difficulties that are associated with opening up pockets and remeshing.
Unstructured meshes of triangles in 2D, or tetrahedra in 3D, are particularly well suited to mesh modification since local refinement and/or coarsening can be achieved without the introduction of hanging nodes or other artifices that often plague adaptation schemes for structured meshes. In this paper we describe the mesh modification technique and present examples of its application to the simulation of time dependent problems involving a domain whose shape is undergoing deformation.
INRIA Sophia-Antipolis, France
Andreas Fabri obtained his Msc. from Saarland University, Germany, in 1990, and his PhD degree from Ecole de Mines de Paris, France, in 1994. He was working at INRIA Sophia-Antipolis, France, in the field of parallel computational geometry. After a one year postdoc at Utrecht University, Netherlands, he returned to INRIA as local responsible for the Computational Geometry Algorithm Library (CGAL) project. End of 1997 he left for industry and joined ABB Corporate Research, Switzerland, where he worked on Internet technology for embedded devices. In summer 2000 he took the opportunity offered by the CGAL consortium to take the project lead and to set up business based on the library.
ABSTRACT: CGAL - The Computational Geometry Algorithm Library
CGAL, the Computational Geometry Algorithms Library, is a geometric data structure and algorithms library developed by a consortium of seven European research institutes. It is written in C++, based on the generic programming paradigm, to provide maximum flexibility and is used worldwide in academic and business settings. CGAL contains 2d and 3d triangulations, multi dimensional search structures, geometric optimisation, arrangements, polyhedral surfaces, etc. There are approximately 1000 classes in the library, 250,000 lines of code, about 1000 manual pages. The library offers support for the main OS/compiler combinations. More information can be found at www.cgal.org. In this talk I give an overview of the library, present some technical choices we made to achieve highest flexibility, and show how the triangulations are used in surface reconstruction and transition mesh generation.
Dept. of Aerospace Engineering & Engineering Mechanics
The University of Texas, Austin
Education: PhD MIT '89.
Position: Professor since 1998, Dept. of Aerospace Engineering and Engineering Mechanics, The University of Texas, Austin .
Major Awards: NSF Young Investigator , AIAA Lawrence Sperry Award for a notable contribution to the advancement of the field of Aeronautics.
Other recognition: (i) Associate Editor of the AIAA Journal since 1996. (ii) has given over 45 invited lectures in the US and Europe.
Publications: over 100 journal papers, conference papers and book chapters.
Areas of activity: (i) Computational grid generation focusing on "Navier-Stokes" meshes for very complex geometries , (ii) Adaptive grid Navier-Stokes methods , (iii) parallel computation with emphasis on dynamic load balancing, (iv) applications in aircraft aerodynamics, unsteady flow-structure interaction ,turbomachinery flows.
Major research accomplishments: (i) pioneered hybrid meshes for viscous 3-D flow simulations, (ii) pioneered grid adaptation for Navier-Stokes methods.
On Hybrid Grids for Viscous Flows involving Complex Geometries
Grid generation for viscous flows simulations involving complex 3-D geometries is investigated. The primary issues of "viscous" grids are discussed. All the major grid topology/generation approaches are presented and compared in terms of strengths and weaknesses. Particular emphasis is given to the mixed-element (hybrid) grids, which are examined critically regarding suitability for Navier-Stokes / Complex geometry simulations. Realistic applications of hybrid meshes are presented.