# FEATool Multiphysics

FEATool Multiphysics ("Finite Element Analysis Toolbox for Multiphysics") is a physics, finite element analysis (FEA), and partial differential equation (PDE) simulation toolbox. FEATool Multiphysics features the ability to model fully coupled heat transfer, fluid dynamics, chemical engineering, structural mechanics, fluid-structure interaction (FSI), electromagnetics, as well as user-defined and custom PDE problems in 1D, 2D (axisymmetry), or 3D, all within a graphical user interface (GUI) or optionally as script files. FEATool has been employed and used in academic research, teaching, and industrial engineering simulation contexts.

## Distinguishing features

FEATool Multiphysics is a fully integrated physics and PDE simulation environment where the modeling process is subdivided into six steps; preprocessing (CAD and geometry modeling), mesh and grid generation, physics and PDE specification, boundary condition specification, solution, and postprocessing and visualization.
| 1. Geometry Mode | 2. Grid Mode | 3. Multiphysics Mode |
| Geometry generation and CAD import | Automatic mesh and grid generation | Subdomain, equation, and coefficient specification |
| 4. Boundary Mode | 5. Solve Mode | 6. Post Mode |
| Boundary condition specification | Solution of PDE systems | Postprocessing and visualization of results |

### OpenFOAM and SU2 CFD & multi-solver interfaces

FEATool has introduced a multi-simulation/solver feature whereby integrated interfaces (UI) to popular open-source solvers are available. This enables several solvers to be used from a single unified GUI and CLI without requiring detailed knowledge of the syntax or peculiarities of each solver.
The CFD solver interfaces allows fluid dynamics problems to be solved with the finite volume CFD solvers OpenFOAM and SU2. Using the SU2 and OpenFOAM GUI interfaces automatically converts fluid dynamics models to compatible corresponding mesh, boundary, and control dictionary files, runs simulations, and afterwards imports and interpolates the resulting solutions back into the toolbox. In this way more advanced, larger, and parallel CFD models, for example including turbulence, can be simulated without leaving the FEATool interface.

### FEniCS multiphysics solver interface

Similar to the OpenFOAM and SU2 solver interfaces, FEATool also features a fully integrated interface to the FEniCS general FEM and multiphysics solver. Using the FEATool-FEniCS interface, as both codes feature PDE definition languages, multiphysics problems can automatically be translated and converted to FEniCS Python definition files, after which the FEniCS solver is called, and the resulting solution re-imported.

### Fully scriptable CLI interface

GUI operation is recorded as equivalent function calls, and therefore in addition to binary formats, FEATool simulation models can also be saved and exported as fully scriptable and editable MATLAB compatible m-script files. The short MATLAB script below illustrates how a complete flow around a cylinder computational fluid dynamics (CFD) benchmark problem can be defined and solved with the FEATool m-script functions (including geometry, grid generation, problem definition, solving, and postprocessing all in a few lines of code). Specifically, custom partial differential equations (PDE) and expressions can simply be entered and evaluated as string expressions as-is, without need for further compilation or writing custom functions.

### External mesh generator interfaces

Similar to the external solver interfaces, FEATool features built-in support for the Gmsh and Triangle mesh generators. If requested instead of the built-in mesh generation algorithm, FEATool will convert and export appropriate Gridgen2D, Gmsh, or Triangle input data files, call the mesh generators through external system calls, and re-import the resulting grids into FEATool.

### Other distinguishing features

* Stand-alone operation (without MATLAB) or can be used as a MATLAB toolbox.
* Fully cross platform MATLAB interoperability including other toolboxes.
* Extensive FEM basis function library (linear and high order conforming P$_1$-P$_5$, non-conforming, bubble, and vector FEM discretizations).
* Support for structured and un-structured line interval, triangles, quadrilaterals, tetrahedral, and hexahedral mesh elements.
* 28 pre-defined equations and multiphysics modes in 1D, 2D Cartesian and cylindrical coordinates, as well as full 3D.
* Support for custom user defined PDE equations.
* Mesh and geometry import, export, and conversion between OpenFOAM, SU2, Dolfin/FEniCS XML, GiD, Gmsh, GMV, Triangle (PSLG), and plain ASCII grid formats.
* Online postprocssing and image export with ParaView Glance, Plotly, and social sharing of results.