“…The correct design and operation of these devices rely on the proper prediction of the flow pattern, the flow regime transition, and global and local flow properties (i.e., the holdup, ε G ; the bubble rise velocity, u b ; the local void fraction, ε G,Local ; and the bubble diameter, d b ). The global and local flow properties of the industrial reactors may be extrapolated from the laboratory facilities applying scale-up methods (Shaikh and Al-Dahhan, 2013). Bubble columns are frequently studied without considering internals ("Open Tube", OT, bubble columns), but, in most industrial applications, internal devices are often added to control heat transfer, to foster bubble break-up or to limit liquid phase back mixing (Youssef Ahmed et al, 2013).…”