In the Movement subtab of the Particles tab, the particle movement is controlled by changing the terms of the governing equation, see the particle momentum equation.

Checking Cunningham Correction activates the corresponding correction method and adjusts the drag force. If this button is unchecked, the Cunningham correction factor is set to . If the button is checked, the value of the mean free path can be entered.

With the Use Particle Motion UDF option, the user can replace the equations for the friction coefficient and external forces by own formulas. When Use Particle Motion UDF is checked, the formulas in the (modified) UDF file are used for all four formulas in the AddiDict simulation instead of the built-in equations. For details on how to modify and compile user defined functions, refer to the appendix on UDF.

In case molecule movement is simulated, only the option Use Particle Motion UDF is available on the Movement tab.