Enhanced bubble migration in turbulent channel flow by an acceleration-dependent drag coefficient

DNS of turbulent bubble-laden channel flow has been used with one-way coupling to investigate consequences of a postulated dependence of acceleration on drag. This dependence is known to hold for converging and diverging steady streamlines, and is here postulated to also exist for the instantaneous acceleration of micro-bubbles that arises from turbulent velocity fluctuations. Bubble segregation is found to be considerably increased through this dependency of drag on acceleration, particularly for smaller bubbles.