# ElmerFEM

**This page is work in progress**

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## ElmerFEM 

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Elmer is a multi-physics simulation software developed by CSC. It can perform coupled mechanical, thermal, fluid, electro-magnetic simulations and can be extended by own equations.

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Some useful links:

 - Elmer homepage: [http://www.elmerfem.org/blog/](http://www.elmerfem.org/blog/)
 - Elmer manuals and tutorials: [https://www.nic.funet.fi/pub/sci/physics/elmer/doc/](https://www.nic.funet.fi/pub/sci/physics/elmer/doc/)
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### How to cite:

_CSC – IT CENTER FOR SCIENCE LTD., 2020. Elmer, Available at: https://www.csc.fi/web/elmer/._

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## Loading the module

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To use ElmerFEM the module needs to be loaded

    module load elmerfem-9.0

This makes the following main commands `ElmerGrid`, `ElmerSolver` available (and `ElmerGUI` can be used on viz to setup the case file). The use of ElmerGUI for simulations is **not** recommended.

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## Running a tutorial case (quick-start for the impatient)

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Copy the tutorial directory (here the linear elastic beam):

    cp -r /share/apps/HPC2/ElmerFEM/tutorials-CL-files/ElasticEigenValues/ linear-elastic-beam-tutorial
    cd linear-elastic-beam-tutorial

Start an interactive session on a node

    srun -t 2:00:00 --pty bash

Create the mesh

    ElmerGrid d 7 2 mesh.FDNEUT

run the solver

    ElmerSolver

Postprocessing would be visualizing the `eigen_values.vtu` file in `paraview` on viz.

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## Setting up a simulation (for new users)

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The follwing steps are needed to configure a simulation case (mostly on base):

1. Create geometry in Gmsh, group and name physical volumes and surfaces (can be done on viz)
2. Create mesh in Gmsh (large meshes can be created from the CLI in a batch job: `gmsh -3 geometry.geo`)
3. Convert the mesh to elmer's format using ElmerGrid, including scaling if needed: `ElmerGrid 14 2 geometry.msh -scale 0.001 0.001 0.001`
4. Create a new project in ElmerGUI (can be done on viz)
    - create project
    - load Elmer mesh (point to the created mesh directory)
    - add equation(s)
    - add material(s)
    - add boundary conditions
    - create sif
    - edit & save sif
5. Edit the `case.sif` file (mesh directory, some other parameters [e.g. calculate PrincipalStresses] can only be added in the sif file, not in the GUI)
6. run simulation `srun ElmerSolver` (or create batch file and submit using sbatch)
7. Postprocessing in ParaView (on viz)
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## An example simulation case from start to finish

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