A bioprocessing mixing vessel comprising a closed container comprising a rotatable impeller comprising a hub having extending arms, each arm comprising upper and lower edges, hub and terminal ends, arm outer and inner faces, and a length from the hub end to the terminal end, the terminal end further comprises a protrusion extending from the lower edge, the protrusion comprising first and second ends, protrusion outer and inner faces, and having a distance between the first and second ends, the protrusion outer face forming an angle in the range of from at least about 45° to about 90° with respect to the arm outer face, wherein the distance between the first and the second ends of the protrusion is about 25% to about 60% of the length from the hub end to the terminal end; and methods of using the mixing vessel, are provided.