Description and Generation of Geometries and Grids for Layered Domains
Dirk Feuchter, Ulrich Stemmermann (Uni Heidelberg)
Solving partial differential equations in geoscientific applications
density driven flow, radio-nuclide transport,
aquifer remediation or saltwater intrusion
imply a complex preprocessing for geometry modelling and grid generation.
Typically the practical relevant geometries in such applications are very anisotropic,
i.e. assemblies of layers with a dimension of many kilometers in x,y-direction
but a dimension of only some meters in z-direction.
Thereby, layers often crop out, sometimes contain lenses,
are faulted or display overhangs (e.g. saltdomes).
Simulations on such layered domains need suitable geometries and grids.
We introduce a method for preprocessing geometry modelling and grid generation.
First we will explain our geometry interfaces "lgm" and "ng"
describing geometries and grids in our numerical simulation system UG.
Second we present an approach to modelling these layered domains
using the gridding methods of a GIS or any data interpolation software
which can describe the thickness of a single layer based on borehole data.
Using a "thickness-approach"
a new algorithm handles the GIS-output
yielding a consistent assembly of all layers
available for the 3D-simulation-process.
Further we present a grid generation approach for such domains
using hybrid meshes with triangles and quadrilaterals in 2D and
prisms, pyramids, tetrahedra and hexahedra in 3D.