ElmerSolver Manual

Abstract

The ElmerSolverManual is part of the documentation of Elmer finite element software. ElmerSolverMan- ual describes the Elmer Solver options common for all specific equation solvers. The different equations solver options are described separately in ElmerModelsManual. The ElmerSolverManual is best used as a referencemanual rather than a concise introduction to the matter. The presentmanual corresponds to Elmer software version 6.0 forWindowsNT andUnix platforms. Lat- est documentations and programversions of Elmer are available (or links are provided) at http://www.csc.fi/elmer. Solving partial differential equation (PDE)modelswith the solver of Elmer requires that a precise description of the problemis given using the so-called solver input file, briefly referred to as the sif file. This file contains user-prepared input datawhich specify the location ofmesh files and control the selection of physicalmodels, material parameters, boundary conditions, initial conditions, stopping tolerances for iterative solvers, etc. In this chapter, the general structure of the file is described. We explain how the input data is organized into different sections and describe the general keyword syntax which is used in these sections to define the values of variousmodel parameters and to control the solution procedures. In the case of simple problem setups the solver input file may be written automatically by the prepro- cessor of Elmer software, so that knowing the solver input file format may be unnecessary. Creating a more complicated setup, or using keywords introduced by the user, however, requires the knowledge of the file format and keyword syntax. In the following the general structure of the input file is first illustrated by using simple examples,without trying to explain all possibilities in an exhaustive manner. We then describe the keyword syntax in more detail, showing also howmodel parameterswhose values depend on solution fields can be created. The later chapters of this manual, and Elmer Models Manual, which focuses on describing the PDE models Elmer can handle, provide more detailed material on specific issues. Elmer Tutorial Manual also gives complete examples of solver input files.