A prandtl layer turbine has a longitudinally extending housing (14) having a fluid inlet port (60) and a fluid outlet port (62); a plurality of spaced apart members (12) rotatably mounted in the housing to transmit motive force between fluid introduced through the fluid inlet port and the members; each member having a pair of smooth opposed surfaces (44, 46), each surface having an inner portion (40) and an outer portion (42). The spaced apart members (12) may include one or more raised areas (48) to assist the thickening of the boundary layer and one or more raised areas (52) to assist in the elimination of the boundary layer. The configuration of the spaced apart members or the configuration of the outlet is varied to alter the fluid through the apparatus. In addition, two or more prandtl layer turbines may be in series and may be nested.
