Entrainment in turbulent flows - Mechanisms and implications

The velocity field of a two-dimensional mixing layer is investigated by a novel technique. This technique combines velocity measurements by Laser Doppler Velocimetry with synchronized flow visualization. This is done in such a way as to permit simultaneous evaluation of the fluid velocity and interface velocity in order to assess where entrainment is taking place. In a parallel study, a way has been devised to examine whether bulk entrainment of outside potential fluid is possible in an axisymmetric jet and conversely whether some of the initially turbulent fluid can detach from the main body of the jet.