(88a) a Novel, Efficient Approach to CFD Simulations of Systems with Break-up and Coalescence of Liquid Droplets

A key challenge in CFD simulations of two phase (gas/liquid) systems containing a dispersed liquid phase relates to the breakage and coalescence of droplets. Sophisticated models such as population balance have been used for that purpose, but the transient simulations and small time-steps associated with such approach leads to non-practical turnaround time for simulations of industrial-scale systems.

In this paper, an advanced droplet size model is developed to account for the local effects of turbulent energy dissipation, number density of particles as well as droplet breakup and coalescence. The CFD model is validated with experimental data from V.M. Alipchenkov, et al. (2004) on dispersed-annular flow in a pipe. The model is then applied to simulate industrial scale large pipe (diameter about 0.8 m). This advanced droplet model, compared with the sophisticated population balance model, is found to produce acceptable results with dramatically reduced simulation time. A comparison is also made between the advanced droplet model and the constant droplet size model â?? to provide guidance when the simplified approach may be appropriate.