Baseline Model for Simulation of Bubbly Flows


Baseline Model for Simulation of Bubbly Flows

Rzehak, R.; Ziegenhein, T.; Krepper, E.; Lucas, D.

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. A large body of work using different closure relations of varying degree of sophistication exists, but no complete, reliable, and robust formulation has been achieved so far.
The closure relations describe phenomena on the small spatial scale of individual bubbles. Hence, for all systems where this small scale behavior is governed by the same physics, the same set of closure relations should be applicable. Therefore it is expected that many systems differing on larger scales can be treated in a unified manner. To show this feasibility we presently consider adiabatic bubbly flows where only momentum is exchanged between liquid and gas phases.
The best available descriptions for the forces acting on the bubbles and the bubble-induced turbulence, which are the relevant aspects requiring closure under these circumstances, have been collected into a baseline model. By keeping all correlations and all parameter values fixed, the applicability of this model to a variety of situations is demonstrated. Future improvements of the model should work for the entire domain of applications.
The model has previously been validated against data for steady flows in pipes and bubble columns. Here, further comparison is made for an airlift column and plume oscillations in bubble columns. A crucial parameter in the model is the bubble size for which reliable measurements are often not available. In this case parametric variations are investigated. From the observed level of agreement between simulation and experiment, issues requiring further investigation will be identified.

  • Lecture (Conference)
    ProcessNet Fachgruppertreffen CFD, 19.-20.03.2015, Lüneburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-22633
Publ.-Id: 22633