There are five drag laws for the particles that can be selected in the Drag Law drop-down list under Drag Parameters.
The spherical, nonspherical, Stokes-Cunningham, and high-Mach-number laws described in Section 22.2.1 are always available, and the dynamic-drag law described in Section 22.6 is available only when one of the droplet breakup models is used in conjunction with unsteady tracking. See Section 22.11.6 for information about enabling the droplet breakup models.
If the spherical law, the high-Mach-number law, or the dynamic-drag law is selected, no further inputs are required. If the nonspherical law is selected, the particle Shape Factor ( in Equation 22.2-9) must be specified. The shape factor value cannot exceed 1. For the Stokes-Cunningham law, the Cunningham Correction factor ( in Equation 22.2-11) must be specified.