The Transient Evolution of Bubbles in Turbulent Channel Flows

Direct numerical simulations of multiphase flows, where every spatial and temporal scale are fully resolved, provide data that allows not only unprecedented insight into the dynamics of the flow but should also aid in the development and testing of models for the unresolved scales in two-fluid and large eddy simulations. DNS of bubbly flows in vertical channels have showed that the structure of such flows is relatively simple but also relatively insensitive to some of the closure terms in equations governing the average flow. Furthermore, most of those simulations have been done for modest Reynolds numbers and uniform bubble size. Here we describe results from a simulation of the transient motion of a larger and more complex system and discuss how the results may help in developing models for the average flow.