Euler-Euler Simulation of Fluid Dynamics and Mass Transfer in Bubbly Flows

CFD simulations of dispersed bubbly flow on the scale of technical equipment are feasible within the Eulerian two-fluid framework of interpenetrating continua. However, accurate numerical predictions rely on suitable closure models. To achieve predictive capability, all details of the closure models have to be fixed in advance without reference to any measured data.
Concerning the fluid dynamics of bubbly flows a baseline model has recently been proposed to this end and shown to work for a range of different applications in a unified manner1,2. This provides a reliable background which is well suited to add more complex physics. Concerning mass transfer in bubbly flows only few studies have been performed to date3. For the mass transfer coefficient, a variety of entirely different closures have been applied in rather similar situations. To facilitate predictive applications, a standard model which is validated for a broad range of conditions yet has to be developed.
The present contribution considers two test cases from the literature, where mass transfer takes place during the absorption of oxygen into water. The first case is a bubbly mixing layer4, the second is concerned with co-current bubble column flow5. The above mentioned baseline model is used for the fluid dynamical part of the simulation model. Two different correlations for the mass transfer coefficient are considered6, which had been used in previous work. Sources of uncertainty in both, models and data, are discussed. Taking into account possible measurement errors, reasonable agreement between simulations and measurements is found for the present situations. Needs for further experimental data to facilitate qualification of a generally applicable model are specified.