Science and Technology of Nuclear Installations 
Volume 2009 (2009), Article ID 320738, 12 pages
doi:10.1155/2009/320738
Research Article

CFD Simulation of Polydispersed Bubbly Two-Phase Flow around an Obstacle

E. Krepper,1 P. Ruyer,2 M. Beyer,1 D. Lucas,1 H.-M. Prasser,3 and N. Seiler2

 1Institute of Safety Research, Forschungszentrum Dresden-Rossendorf (FZD), P.O. Box 510119, 01314 Dresden, Germany
2Institut de Radioprotection et de Sûreté Nucléaire, CE Cadarache, Bât. 700, BP 3, 13 115 Saint Paul lez Durance Cedex, France
3Institute of Energy Technology, ETH-Zürich, Sonneggstrasse 3, 8092 Zürich, Switzerland
Received 10 January 2008; Accepted 18 February 2008

Recommended by Iztok Tiselj

Abstract

This paper concerns the model of a polydispersed bubble population in the frame of an ensemble averaged two-phase flow formulation. The ability of the moment density approach to represent bubble population size distribution within a multi-dimensional CFD code based on the two-fluid model is studied. Two different methods describing the polydispersion are presented: (i) a moment density method, developed at IRSN, to model the bubble size distribution function and (ii) a population balance method considering several different velocity fields of the gaseous phase. The first method is implemented in the Neptune_CFD code, whereas the second method is implemented in the CFD code ANSYS/CFX. Both methods consider coalescence and breakup phenomena and momentum interphase transfers related to drag and lift forces. Air-water bubbly flows in a vertical pipe with obstacle of the TOPFLOW experiments series performed at FZD are then used as simulations test cases. The numerical results, obtained with Neptune_CFD and with ANSYS/CFX, allow attesting the validity of the approaches. Perspectives concerning the improvement of the models, their validation, as well as the extension of their applicability range are discussed.