Void fraction propagation in a bubbly two-phase flow with expansion effects

This paper is concerned with an analysis of wave propagation in dilute bubbly flow in a continuous liquid with bubble radius variations due to expansion effects. A one-dimensional, time-dependent, two-phase volume-averaged model was derived to study the interaction effects in the bubble flow regime. Potential inviscid flow around the bubbles was considered for the evaluation of the averaged flow description in order to get closure relationships. The closed model was used to derive the averaged wave equation that is used to describe the propagation features of the void fraction waves and to investigate the linear stability of the bubble flow regime. The averaged model was solved using the finite difference technique with an implicit scheme to study the importance of the radial reaction force effects due to bubble radius variations under transient conditions. The effects of temperature variations although small, were also analysed.