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

Abstract EN

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.