Due to the small aspect ratio of ice-sheets, but also glaciers, creating a mesh for a glacier geometry or an ice-sheet geometry cannot generally be done using classical meshers. Our experience in modelling different glaciers, ice-caps and ice-sheets, is that a vertically structured mesh is very often the best solution. Such a mesh can be constructed by first meshing the footprint of the glacier contour and then extruding this footprint vertically. The extrusion can be done either before running the simulation or using the internal mesh extrusion feature in Elmer, as presented below.
This Section presents some tools that have been developed and are used to construct a mesh for a glacier type geometry.
The characteristics of these different tools are listed in the following tabular:
|Tool||DIM||Initial Mesh||Data (bed and surface)||Interpolation|
|MshGlacier||2D||2D square 1×1||(x,z) points||linear / cubic spline|
|ExtrudeMesh 1)||3D||2D footprint||(x,y,z) points2)||
|MshGlacierDEM||3D||3D footprint x 1m||DEMs||bilinear|
|MshGlacierSynthetic||2D & 3D||2D or 3D footprint x 1m||functions||N/A|
1) possibility to include boundary layer at top or bottom 2) randomly distributed supporting points
Elmer proposes special solvers to perform efficient mesh and variables manipulations when the mesh is structured. Elmer also allows to perform internal extrusion during the simulation to create such structured mesh from a 2D-footprint. These features for structured meshes are documented here. The material course presented in April 2013 at Edmonton takes into account some of these features. More information can also be found in the Elmer documentation.