CFD simulation of the flow field in a bubble column reactor: Importance of the drag force formulation to describe regime transitions

This paper deals with the simulation of a quasi two-dimensional bubble column. In particular, the aim is to predict regime transitions occuring in bubble column reactors, which is very important for their design. It is shown that taking into account bubble–bubble interactions through a drag coefficient depending on the local void fraction [M. Simonnet, C. Gentric, E. Olmos, N. Midoux, Experimental determination of the drag coefficient in a swarm of bubbles, Chem. Eng. Sci. 62 (2007) 858–866] allows to predict the onset of the regime transitions. This has been verified both with the Eulerian and Lagrangian approaches. It is also shown that the use of this drag correlation allows to reproduce some typical characteristics of the different regimes (velocity profiles becoming parabolic in the transition regime, typical transient phenomena, accumulation of large bubbles in the column centre in the transition and heterogeneous regimes).