# Run-time Inputs

Run-time inputs are used to control the simulation setup such as the grid, solver settings, geometry, boundary conditions etc. These `<key> = <value(s)>` pairs are saved in a text file, with any file name, that is passed to the MFIX-Exa executable at run time:

    ./mfix my_project.inputs

Note

Traditionally, input files have been named `inputs`. However, it is recommended that you provide a descriptive name with an extension of `.inputs` such as `fluid_bed.inputs`

The input text file looks something like this:

    # Run settings
    mfix.stop_time = 10.0 # inline comment

    # Solver settings
    nodal_proj.verbose = 0
    nodal_proj.maxiter = 1000

where comments are denoted with a `#`. If a value is not specified for a key, the default value will be used.

The following sections contain information addressing the input keywords and values for setting up a problem. Pay special attention to any prefixes for the keywords such as `mfix`, `amr`, `geometry`, `nodal_proj` etc.

- Initialization
- Time stepping
- Defining the domain
- Specifying a geometry
- Mesh, grids, and tiles
- Multigrid solvers
- Model options
- Fluid model
- Solids model
- Species definitions
- Defining chemical reactions
- Example inputs
- Regions definitions
- Initial conditions
- Boundary conditions
- Porous media definitions
- Output
- Advanced
- Multiple Program Multiple Data (MPMD)