The following set of IBIS commands are general in purpose and will appear often in IBIS programs.
The bforce command is used to apply a uniform force on the fluid in a specified tubular region. This force is used to approximate a pressure drop from one end of the tubular region to the other, and is used to drive a flow. The particle command specifies the properties of the fluid marker particles. The source command tells IBIS that there are fluid sources and sinks in the domain, and allocates memory for their existence. The units command is used internally to scale the domain and time parameters of the simulation. It eliminates the users responsibility for transforming the physical units of the problem to computational units and vice-versa.