On the Modeling of Gas Bubble Evolution and Transport Using Coupled Level-Set/CFD Method

The ability to predict the shape of gas/liquid interface is important for various multiphase flow and heat transfer applications. Specific issues of interest to nuclear reactor thermal hydraulics include the evolution of the shape of bubbles attached to solid surfaces during nucleation, bubble/surface interactions in complex geometries, etc. The development of an innovative approach to model the time-dependent shape of gas/liquid interfaces is discussed. The proposed approach combines a modified level-set method with an advanced computational fluid dynamics code, NPHASE. The coupled numerical solver can be used to simulate the evolution of gas/liquid interfaces in two-phase flows for a variety of geometries and flow conditions.

The novel aspects of the work include the development of direct coupling between the level-set algorithm and the finite-volume code NPHASE, the development of a novel mass conservation algorithm for the level-set method, the analysis of the influence of fluid physical properties on the predicted bubble flow conditions, and the use of a three-dimensional model to simulate gas bubble flow in channels of various geometries and orientations.