Abstract: A single or multi-stage centrifugal pump or mixer duplex shear force rotor. The rotor is circular and consists of two non-parallel shrouds with inner, opposing faces. The driven shroud contains a center opening. The rotor has an open, unobstructed entrance section with no raised ribs and includes a protrusion designed to force-feed the discharge section in a smooth laminar flow pattern. The discharge section incorporates a series of raised ribs. The raised ribs begin at the peripheral edge of the drive and driven shrouds and extend in a direction towards the center of the drive and driven shroud and terminate approximately 50% of the distance from the periphery and the center of the rotor. Cast-in-place spacers space the drive and driven shrouds. Alternatively, the rotor can include no raised ribs. In addition, the raised ribs can have a cross-section that includes a tapered trailing edge to reduce wear. The rotor can also be used without inclusion of the raised ribs.