Abstract: A fluid entrainment apparatus is provided which operates to mix a first fluid stream with a second fluid stream. The apparatus includes first and second fluid flow conduits. The first fluid flow conduit includes a nozzle portion having a converging bore through which the first fluid is accelerated. Additionally, the second fluid flow conduit includes a nozzle portion having a converging bore, a duct portion having a generally cylindrical bore, and a diffuser portion having a diverging bore. The nozzle portion of the second fluid flow conduit is mounted with respect to the nozzle portion of the first fluid flow conduit such that an annular port is formed through which the second fluid passes to mix with the first fluid. Additional fluid mixing occurs in the duct portion and the diffuser portion. The fluid entrainment apparatus may be configured for use within a vehicle exhaust system.