# Parametrized Simulation using CFG files

The Model CFG (`.cfg`) files allow to pass command line options to Feel++ applications. In particular, it allows to

• setup the output directory

• setup the mesh

• setup the time stepping

• define the solution strategy and configure the linear/non-linear algebraic solvers.

• other options specific to the toolbox used

``````directory=toolboxes/fluid/TurekHron/cfd3/P2P1G1 (1)

case.dimension=2 (2)
case.discretization=P2P1G1 (3)

[fluid] (4)
filename=$cfgdir/cfd3.json (5) mesh.filename=$cfgdir/cfd.geo (6)
gmsh.hsize=0.03 (7)

solver=Newton (8)

pc-type=lu (9)

bdf.order=2 (10)

[ts]
time-step=0.01 (11)
time-final=10 (12)``````
 1 the directory where the results are stored 2 the dimension (2d/3d) of the application 3 the discretization choosen (specific to the toolbox) 4 the prefix of option 5 the path of the json file 6 the path of geo/mesh file 7 characterist size of the mesh 8 type of non linear solver (specific to fluid toolbox) 9 type of preconditioner 10 order of BDF tiem scheme (specific to fluid toolbox) 11 time step 12 time final

If the mesh file is stored on a remote storage as Girder, the `mesh.filename` option in the previous listing can be replaced by

``mesh.filename=girder:{file:5af862d6b0e9574027047fc8}``

where `5af862d6b0e9574027047fc8` is the id of the mesh file in the Girder platform. All options for Girder access are listed here :

Option Default value Description

`url`

girder.math.unistra.fr

url of a Girder platform

`file`

<no default value>

one or several file id(s)

`api_key`

<no default value>

an authentication key