A device for cavitational mixing, the device comprising: a) a housing _comprising a chamber defined by a cylindrical wall having a longitudinal axis, the chamber further partially defined by a pair of end walls; b) a stator forming a portion of an end wall, the stator comprising a circumferential external surface facing the cylindrical wall and a first plurality of stator bore holes oriented perpendicular to the housing longitudinal axis; and c) a rotor mounted on a shaft , the rotor positioned within the housing chamber , the rotor comprising a circumferential internal surface facing the circumferential external surface of the stator , the circumferential internal surface of the rotor having a second plurality of rotor bore holes oriented perpendicular to the housing longitudinal axis, wherein the stator and the rotor are positioned such that the first plurality of stator bore holes are substantially in register to the second plurality of rotor bore holes , and when the rotor is rotated relative to the stator each of the second plurality of rotor bore holes passes a stator bore hole of the first plurality of stator bore holes , and wherein each of the bore holes in the second plurality of rotor bore holes and each of the bore holes in the first plurality of stator bore holes has substantially the same diameter, characterized in that the first plurality of stator bore holes have an opening along the circumferential external surface of the stator and a closed end positioned within the stator , and the second plurality of rotor bore holes have an opening along the circumferential internal surface of the rotor and a closed end positioned within the rotor . a) a housing _comprising a chamber defined by a cylindrical wall having a longitudinal axis, the chamber further partially defined by a pair of end walls; b) a stator forming a portion of an end wall, the stator comprising a circumferential external surface facing the cylindrical wall and a first plurality of stator bore holes oriented perpendicular to the housing longitudinal axis; and c) a rotor mounted on a shaft , the rotor positioned within the housing chamber , the rotor comprising a circumferential internal surface facing the circumferential external surface of the stator , the circumferential internal surface of the rotor having a second plurality of rotor bore holes oriented perpendicular to the housing longitudinal axis, wherein the stator and the rotor are positioned such that the first plurality of stator bore holes are substantially in register to the second plurality of rotor bore holes , and when the rotor is rotated relative to the stator each of the second plurality of rotor bore holes passes a stator bore hole of the first plurality of stator bore holes , and wherein each of the bore holes in the second plurality of rotor bore holes and each of the bore holes in the first plurality of stator bore holes has substantially the same diameter, characterized in that the first plurality of stator bore holes have an opening along the circumferential external surface of the stator and a closed end positioned within the stator , and the second plurality of rotor bore holes have an opening along the circumferential internal surface of the rotor and a closed end positioned within the rotor . <EOS>