Elmer is an open-source, parallel, Finite Element code, mainly developed by the CSC in Finland. The ice sheet / ice flow model Elmer/Ice is based on Elmer and includes developments related to glaciological problems.
Elmer/Ice includes a large number of dedicated solvers and user functions which are described in these pages.
Elmer/Ice solves the full-Stokes equations for various ice rheologies (classical Glen’s flow law, anisotropic laws and porous compressible firn/snow law). It includes also solvers for the classical asymptotical expansions of the Stokes equations, namely the Shallow Ice Approximation (SIA) and the Shallow Shelf Approximation (SSA). All these equations can be solved diagnostically or in transient, allowing the displacement of the boundaries. By the multi-physics approach of Elmer it is also possible to solve coupled problems, such as thermo-mechanically coupled ice flow.
Elmer/Ice includes solvers for internal variables evolution, such as fabric for the anisotropic rheology or the density for the firn/snow law. Age of ice, temperature, stress and strain-rate fields have also their own solver.
In terms of boundary conditions, Elmer/Ice includes various friction laws (classical Weertman sliding law or effective-pressure dependent friction laws) and two basal hydrology model to evaluate the effective pressure. For the the grounding line dynamics, Elmer/Ice solves the contact problem between ice and bedrock defined by a variational inequality.
Elmer/Ice includes inverse methods to infer largely undetermined parameters such as the basal friction or ice fluidity.
Elmer/Ice also includes dedicated mesh tools specially designed to ice-sheet and glacier type geometries. Three-dimensional meshes are obtained using plane view unstructured mesh constructed using the tool YAMS and then vertically extruded.