Analysis and modeling of bubble-induced agitation from direct numerical simulation of homogeneous bubbly flows

Using direct numerical simulations of homogeneous bubbly flows, an analysis of velocity fluctuations is performed and a methodology for development of a bubble-induced agitation (pseudoturbulence) model described. This process is based on separating two causes of velocity fluctuations in the liquid: Agitation resulting from wakes and their collective interactions; and nonturbulent fluctuations due to averaged wakes and potential flows around bubbles. An energy conversion signature is observed, revealing the importance of nonlinear interactions. A model is proposed which gives satisfactory results on our database for a wide range of bubble Reynolds numbers and is consistent with experiments.