The design possibilities of counterrotating screws give better "function density," meaning they can perform more process functions - such as feeding, melting, mixing, pumping, and venting - in a given L/D than are possible in corotation.
As the two screws turn in corotation, the left and right lobes approach the intermesh region from the opposite direction.
In corotation, dispersive mixing occurs largely outside he intermesh region by pressure-flow forces between the lobe and barrel wall.
According to the prevailing theories, based on the restricted three-body framework (Neptune-Galatea-arcs) with a conservative disturbing potential, these arcs are radially and lon gitudinally confined by the corotation
resonance potential of the inner moon Galatea.