Bubble dispersion and interphase coupling in a free-shear flow

Abstract

The interaction of a dilute dispersed cloud of microbubbles with a planar free-shear layer is investigated experimentally. The emphasis of this study is on the role of the coherent large scales of the flow in the bubble dispersion field and the energy redistribution within the carrier phase. The interphase momentum transfer integrals that appear in the volume-averaged momentum and energy equations account for redistribution of energy from potential to kinetic within the carrier phase. This results from both the hydrostatic and dynamic pressure fields. The energy redistribution within the carrier phase that is associated with the large-scale structures of the flow possesses significant inhomogeneities within the mixing layer. Peaks of enhanced kinetic energy generation are associated with the upwelling regions at the downstream edge of the coherent vortex cores, and weaker peaks of kinetic energy destruction are associated with downwelling regions. The contribution of the quasi-steady drag term to the total energy redistribution is found to be dominant in only a limited region of the flow field.