Génération de maillages non structurés volumiques de modèles géologiques pour la simulation de phénomènes physiques
Arnaud Botella. ( 2016 )
Université de Lorraine
Abstract
The geomodeling main goals are to represent and understand the subsurface. The geological structures have an important role for understanding and predicting its physical behavior. We defined a geological model as a set of structures and their connections. The meshes are numerical supports to solve the equations modeling the subsurface physics. So it is important to build a mesh representing a geological model to take into account the impact of these structures on the subsurface phenomena. The objective of this thesis is to develop volumetric meshing methods for geological models. We propose a volumetric unstructured meshing method to build two mesh types: an adaptive tetrahedral mesh and an hex-dominant mesh (i.e. made of tetrahedra, triangular prisms, quadrilateral pyramids and hexahedra). This method generates first a tetrahedral mesh that can respect different types of data: (1) a geological model defined by its boundaries to capture the structures in the volumetric mesh, (2) well paths represented as a set of segments, (3) a mesh size property to control the mesh element edge length and (4) a direction field to control vertex/element alignments inside the mesh to increase some features such as elements with right angles. Then, this tetrahedral mesh can be transformed in a mixed-element mesh. The method recognizes combinatorial relationships between tetrahedra to identify new elements such as prisms, pyramids and hexahedra. This method is then used to generate meshes whose features correspond to a given application in order to reduce errors during numerical computation. Several application domains are considered such as geomechanical, ow and wave propagation simulations.
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BibTeX Reference
@PHDTHESIS{, author = { Botella, Arnaud }, title = { Génération de maillages non structurés volumiques de modèles géologiques pour la simulation de phénomènes physiques }, year = { 2016 }, school = { Université de Lorraine }, url = { http://docnum.univ-lorraine.fr/public/DDOC_T_2016_0097_BOTELLA.pdf }, abstract = { The geomodeling main goals are to represent and understand the subsurface. The geological structures have an important role for understanding and predicting its physical behavior. We defined a geological model as a set of structures and their connections. The meshes are numerical supports to solve the equations modeling the subsurface physics. So it is important to build a mesh representing a geological model to take into account the impact of these structures on the subsurface phenomena. The objective of this thesis is to develop volumetric meshing methods for geological models. We propose a volumetric unstructured meshing method to build two mesh types: an adaptive tetrahedral mesh and an hex-dominant mesh (i.e. made of tetrahedra, triangular prisms, quadrilateral pyramids and hexahedra). This method generates first a tetrahedral mesh that can respect different types of data: (1) a geological model defined by its boundaries to capture the structures in the volumetric mesh, (2) well paths represented as a set of segments, (3) a mesh size property to control the mesh element edge length and (4) a direction field to control vertex/element alignments inside the mesh to increase some features such as elements with right angles. Then, this tetrahedral mesh can be transformed in a mixed-element mesh. The method recognizes combinatorial relationships between tetrahedra to identify new elements such as prisms, pyramids and hexahedra. This method is then used to generate meshes whose features correspond to a given application in order to reduce errors during numerical computation. Several application domains are considered such as geomechanical, ow and wave propagation simulations. } }