3.5 Forcing

An optional section of the file allows forcing functions to be defined. These are enclosed in the FORCING tag. The forcing type is enclosed within the FORCE tag and expressed in the file as:

The force type can be any of the following:

• "Absorption"
• "Body"
• "Programmatic"
• "Noise"

3.5.1 Absorption

This force type allows the user to apply an absorption layer (essentially a porous region) anywhere in the domain. The user may also specify a velocity profile to be imposed at the start of this layer, and in the event of a time-dependent simulation, this profile can be modulated with a time-dependent function. These velocity functions and the function defining the region in which to apply the absorption layer are expressed in the CONDITIONS section, however the name of these functions are defined here by the COEFF tag for the layer, the REFFLOW tag for the velocity profile, and the REFFLOWTIME for the time-dependent function.

3.5.2 Body

This force type specifies the name of a body forcing function expressed in the CONDITIONS section.

3.5.3 Programmatic

This force type allows a forcing function to be applied directly within the code, thus it has no associated function.

3.5.4 Noise

This force type allows the user to specify the magnitude of a white noise force. Optional arguments can also be used to define the frequency in time steps to recompute the noise (default is never) and the number of time steps to apply the noise (default is the entire simulation).