Eric Saltel

Automatic mesh generator with specified boundary

Abstract For the purpose of finite element computation for 2D or 3D geometry, one needs an appropriate mesh of the considered domain. A class of full automatic methods, derived from Voronois theory, is suitable to generate the mesh of any shape via a set of points which describes the geometry. Such methods providing triangles in 2D and tetrahedra in 3D can be seen, after an adequate initialization, as the merger of each given point in an existing mesh using an updating process. Unfortunately, this mesh which contains all the given points does not contain, in general, the edges (or the faces) of the boundary which are the natural data to be satisfied. The aim of this paper is, after a brief survey of the different steps of the above method, to point out the problem of the exact fitting of the given boundary and to present a method which guarantees this crucial property.

Delaunay mesh generation governed by metric specifications. Part I algorithms

Abstract This paper proposes a Delaunay-type mesh generation algorithm governed by a metric map. The classical method is briefly established and then the different steps it involves are extended. It will be shown that the proposed method applies in three dimensions. The work is divided in two parts. Part I, i.e. the present paper, is devoted to the algorithmical aspects while Part II will present numerous application examples in the context of finite element computations.

Fully automatic mesh generator for 3D domains of any shape

Abstract Devoted to mesh generation of 3D domains, this paper examines the different approaches actually in progress. A new method is introduced which can be seen as a variant of the Delaunay-Voronoi tesselation coupled with a control of the given boundary used to define the domain under consideration.

From arteriographies to computational flow in saccular aneurisms: the INRIA experience

Saccular aneurisms illustrate usefulness and possible techniques of image-based modeling of flow in diseased vessels. Aneurism flow is investigated in order to estimate the rupture risk, assuming that the pressure is the major factor and that high-pressure zones are correlated to within-wall strong-stress concentrations. Computational flow is also aimed at providing additional arguments for the treatment strategy. Angiographies of aneurismal vessels of large and medium size are processed to provide three-dimensional reconstruction of the vessel region of interest. Different reconstruction techniques are used for a side and a terminal aneurisms. Reconstruction techniques may lead to different geometries especially with poor input data. The associated facetisation is improved to get a computation-adapted surface triangulation, after a treatment of vessel ends and mesh adaptation. Once the volumic mesh is obtained, the pulsatile flow of an incompressible Newtonian blood is computed using in vivo non-invasive flowmetry and the finite element method. High pressure zones are observed in the aneurism cavity. The pressure magnitude in the aneurism, the location and the size of high pressure zones depend mainly on the aneurism implantation on the vessel wall and its orientation with respect to the blood flux in the upstream vessel. The stronger the blood impacts on the aneurismal wall the higher the pressure. The state of the aneurism neck, where a high-pressure zone can occur, and the location of the aneurism, with an easy access or not, give arguments for the choice between coiling and surgical clipping. Mesh size and 3D reconstruction procedure affect the numerical results. Helpful qualitative data are provided rather than accurate quantitative results in the context of multimodeling.

Automatic 3D mesh generation with prescribed meshed boundaries (alternator)

Different approaches for the mesh generation of 3-D domains are reviewed. A novel method is introduced which can be seen as a variant of Delaunay-Voronoi tesselation coupled with control of the given boundary used to define the domain to be meshed. Special consideration is given to an algorithm for the treatment of the specified boundaries and a process for the creation of internal points to obtain good shape elements. The method was validated by tests on several applications. >

Automatic mesh generation for 3D domains with application in fluid mechanics, structures, electrotechnics and aerospace problems

Finite element simulation requires the generation of an adequat mesh recovering the domain of interest. Domains, assumed of arbitrary shape, are generally described via the data of their boundaries (a list of faces due to CAD-CAM systems).