Finite element modelling in the clouds

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The finite element method (FEM) is widely used in engineering to represent mechanisms in space and time. Its mathematical basis is pretty complicated, but some Python packages facilitate problem definition and solving. But don't think FEM is easy even with the simplest FEM package : deep learning is popcorn compared to FEM.

Once you decide you need FEM in your toolbox, you can use a commercial software, or one of the numerous open source packages waiting to be downloaded, most of them not coming with a graphical user interface. To let you interact dynamically with your models, most open source tools, like FEniCS, are written in Python. And to allow running most of the job fast, FEM packages rely on low level programming languages like C++ and FORTRAN. Sometimes, installing a working environment is subjected to bugs.

Introducingā€¦ šŸ„ a FEniCS setup on Nextjournal. Nextjournal offers cloud science computing environments with a notebook interface. As usual, there are free and paid plans, but for now they offer a low restrictive free plan, so you can use a FEniCS computing environment for free, under a fair use policy.

Andrea Amantini, from Nextjournal, and I created a fully functional computing environment for FEniCS version 2019.1 with two lines of code.

Install your own environment

You can install FEniCS yourself in a basic Python environment by creating a new notebook, selecting Python, creating a Bash cell type, then paste

conda install -c conda-forge fenics=2019.1
pip install dijitso

The conda command installs FEniCS with all its dependencies. But the conda installation of dijitso, a Python module on which FEniCS depends, looks for a non-existing cache directory. The pip command installs dijitso correctly.Ā To run this command, you will need to change the Machine type to a 7.5 GB RAM to avoid memory errors (Gear > Machine Type > 2 vCPUs, 7.5 GB RAM). While you are there, make sure that the Protocol is set to Jupyter, since the Nextjournal protocol don't seem to be able to plot the results.

fenics installation gif

Use the image

A quicker way is to benefit from the super-powers of Nextjournal by using an already functional environment that I published.

Create a notebook with a Python environment (or any other). Click on the gear. Under Environment, click on Import environmentā€¦, then Load all profiles, then search for essicolo, which is my username. Then select FEniCS 2019.1. You will now be able to run from fenics import * then begin coding.

fenics setup gif

If you need an extra package, check first if it's already installed by creating a Bash cell, then run conda list. If it's not there, you can install it with conda or pip in a Bash cell.

Check out the first FEniCS tutorial and enjoy!

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