• Fenics examples

    Fenics examples

    Logg, K. Mardal, G. Wells et al.

    fenics examples

    Springer, Download from Launchpad. We see JIT compilation of finite element code, i. This is done once and will not be done again with different mesh. The function boundary defines boundary of the domain and bc represents Dirichlet boundary condition on space V.

    Finally we create finite-element function u on space V. TrialFunction and TestFunction were only thought arguments of multi-linear forms - not a real function with its values in memory. Note that the solution process can be controlled in a much detailed way.

    Task 2. Try also running it in parallel using mpirun command. Task 3. Task 4. Use Constant class for k to avoid form recompilation when changing k. Very short introduction to Python. Heat equation. Enter search terms or a module, class or function name. Navigation index next previous FEniCS tutorial 1.

    UFL Unified Form Language is a specific language for declaration of finite element discretizations of variational forms.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.

    If nothing happens, download GitHub Desktop and try again. If nothing happens, download Xcode and try again. If nothing happens, download the GitHub extension for Visual Studio and try again.

    This repository contains all source files, published documents, and example programs for the FEniCS Tutorial. Skip to content. Dismiss Join GitHub today GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Sign up. Source files and published documents for the FEniCS tutorial. TeX Branch: master. Find file. Sign in Sign up. Go back. Launching Xcode If nothing happens, download Xcode and try again.

    Latest commit. Anders Logg Small fix comment from Andreas Felderer. Latest commit bfc Oct 30, You signed in with another tab or window. Reload to refresh your session. You signed out in another tab or window. Oct 28, Add new scan of comments from referee 4. Nov 4, Want to get up and running quickly? Try the fenicsproject script in Quickstart. Docker allows FEniCS and its dependencies to be packaged into a standard format for identical deployment almost anywhere. Docker containers are lightweight and are based on open standards that run on all major Linux distributions, macOS and Microsoft Windows platforms.

    Install Docker by following these instructions. For Linux, use a standard terminal. You may need to prepend sudo to the commands below. In addition, if you are executing docker via fenicsproject script, you must prepend it with sudo -E. To allow sudo -less use, refer to the installation instructions for your distribution to add your user to the docker group. Not working? Check out the Troubleshooting section.

    To pull the quay. This ID is unique to your computer and this container and will be different to the one above. The results will be outputted to the file poisson. How to open this file with a visualisation tool is covered in the next section. Most users want to continue using the text editor, version control and other tools already installed on their computers, and just use the Docker container to run FEniCS.

    Permissions issues on Linux? Note that all paths are absolute paths. In this case, all files in my-work-directory will be shared into the container. We recommend keeping the source code and generated results for your projects in this shared directory, easily accessible on the host machine. Every container can be given a name so it can be easily referred to it in the future by passing the --name flag to the docker run command, e.

    FEniCS Containers latest. Quickstart 2. Introduction 2. Installing Docker 2. Sharing files from the host into the container 2.

    fenics examples

    Naming a container 3. Available FEniCS images 4. Suggested workflows 5. Running Jupyter notebooks 6.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. If nothing happens, download GitHub Desktop and try again.

    If nothing happens, download Xcode and try again. If nothing happens, download the GitHub extension for Visual Studio and try again. Solving some examples of partial differential equations PDE using fenics.

    Skip to content. Dismiss Join GitHub today GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Sign up. Python Branch: master. Find file. Sign in Sign up.

    Go back. Launching Xcode If nothing happens, download Xcode and try again. Latest commit Fetching latest commit…. To represent the results use paraview. Some results Heat equation with Dirichlet boundaries Heat equation with Dirichlet boundaries 2 Heat equation with Dirichlet and natural Neumann boundaries Heat equation with mix boundaries.

    You signed in with another tab or window. Reload to refresh your session. You signed out in another tab or window.The examples in the section Fundamentals illustrate that solving linear, stationary PDE problems with the aid of FEniCS is easy and requires little programming.

    That is, FEniCS automates the spatial discretization by the finite element method. The solution of nonlinear problems, as we showed in the section Nonlinear Problemscan also be automated cf.

    The section Solving the Nonlinear Variational Problem Directlybut many scientists will prefer to code the solution strategy of the nonlinear problem themselves and experiment with various combinations of strategies in difficult problems.

    Time-dependent problems are somewhat similar in this respect: we have to add a time discretization scheme, which is often quite simple, making it natural to explicitly code the details of the scheme so that the programmer has full control.

    We shall explain how easily this is accomplished through examples. Our time-dependent model problem for teaching purposes is naturally the simplest extension of the Poisson problem into the time domain, i. Here, varies with space and time, e. The source function and the boundary values may also vary with space and time.

    FEniCS Project

    The initial condition is a function of space only. A straightforward approach to solving time-dependent PDEs by the finite element method is to first discretize the time derivative by a finite difference approximation, which yields a recursive set of stationary problems, and then turn each stationary problem into a variational formulation.

    Let superscript denote a quantity at timewhere is an integer counting time levels. For example, means at time level. A finite difference discretization in time first consists in sampling the PDE at some time level, say :. The time-derivative can be approximated by a finite difference. For simplicity and stability reasons we choose a simple backward difference:. Inserting this approximation in the PDE yields. This is our time-discrete version of the diffusion PDE problem. Reordering the last equation so that appears on the left-hand side only, yields a recursive set of spatial stationary problems for assuming is known from computations at the previous time level :.

    A Gallery of finite element solvers

    Givenwe can solve for,and so on. We use a finite element method to solve the time-discrete equations which still have spatial differential operators. This requires turning the equations into weak forms. As usual, we multiply by a test function and integrate second-derivatives by parts.

    Introducing the symbol for which is natural in the program toothe resulting weak form can be conveniently written in the standard notation: for the initial step and for a general step, where. The continuous variational problem is to find such that holds for alland then find such that for all.

    Approximate solutions in space are found by restricting the functional spaces and to finite-dimensional spaces, exactly as we have done in the Poisson problems. We shall use the symbol for the finite element approximation at time. In case we need to distinguish this space-time discrete approximation from the exact solution of the continuous diffusion problem, we use for the latter.

    By we mean, from now on, the finite element approximation of the solution at time. Note that the forms and are identical to the forms met in the section Computing Derivativesexcept that the test and trial functions are now scalar fields and not vector fields. Instead of solving an equation for by a finite element method, i.

    fenics examples

    That is, ifwe simply setwhere are the coordinates of node number. We refer to these two strategies as computing the initial condition by either projecting or interpolating. Both operations are easy to compute through one statement, using either the project or interpolate function. Our program needs to perform the time stepping explicitly, but can rely on FEniCS to easily compute,andand solve the linear systems for the unknowns. We realize that does not depend on time, which means that its associated matrix also will be time independent.

    Therefore, it is wise to explicitly create matrices and vectors as in the section A Linear Algebra Formulation. The matrix arising from can be computed prior to the time stepping, so that we only need to compute the right-hand sidecorresponding toin each pass in the time loop.

    Let us express the solution procedure in algorithmic form, writing for the unknown spatial function at the new time level and for the spatial solution at one earlier time level :.Andy Terrel also notes that the FEniCS software package was originally compiled at the University of Chicagowhose mascot is a phoenix, which likely inspired the name. A discussion of the topic can be found here on the FEniCS launchpad. This article acts as an introduction to the Python programming language and specifically its use with FEniCS.

    Finite element using Python and matplotlib

    The Python code below, taken from an example problem found here: Egm The structure of the example code can be applied to many problems but will require varying degrees of modification. A Python code file can quickly be created from the Linux terminal. Entering the command "gedit" will open a blank document. Simply write the code in this document and save it into the desired directory with a.

    The file can be reopened for editing by entering "gedit filename. The code can be run by entering "Python filename. Code can also be written using iPython, an interactive Python with many benefits and additional capabilities. Begin iPython by entering "ipython" in the terminal. You can quit iPython at any time by entering "quit". The code can be saved to your current directory by entering "save filename. For example, "save example.

    The code here imports classes like Interval, Functionspace, Function, etc. FEniCS relies heavily on these classes so this will normally be the first line in your Python code. Including "from" causes the statement to repeatedly define names from the module. The example interval runs from 0 to 1 with 20 divisions.

    FEniCS Project

    We then define a discrete function space V over the mesh.FEniCS enables users to quickly translate scientific models into efficient finite element code. FEniCS runs on a multitude of platforms ranging from laptops to high-performance clusters. The above code snippet also shows how to define a suitable finite element function space, using continuous piecewise quadratic vector-valued functions for the velocity and continuous piecewise linear functions for the pressure Taylor-Hood.

    The computational domain and mesh are also easily created with FEniCS, here defined by three spheres immersed in a 3D channel. The figure shows the von Mises stresses computed from a nonlinear thermomechanical FEniCS simulation of a turbocharger. The finite element system of linear equations comprises more than 3. Choose between Docker containers, binary packages and source code. Visit our installation page to get the latest version of FEniCS.

    fenics examples

    FEniCS comes with extensive documentation and numerous examples. The FEniCS Project is developed and maintained as a freely available, open-source project by a global community of scientists and software developers.

    CAD to FEniCS example

    If you like FEniCS and want to support our mission to produce the best possible platform for open-source computing, consider making a donation to our project.

    FEniCS Project Define function space. Define variational problem. Compute solution. Define domain. Generate mesh. FEniCS Project. Copyright Vega Wordpress Theme by LyraThemes.


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