Some issues related to the modeling of interfacial areas in gas–liquid flows, II. Modeling the source terms for dispersed flows

The first part of this paper dealt with the conceptual issues encountered in the definition of the interfacial area and in the derivation of a transport equation. The second part has the following objectives: 1. to address the closure issues for the source terms appearing in the transport equation when dealing with a bubbly flow in a vertical pipe; 2. to provide a list of open questions to be answered before introducing a transport equation for the interfacial area concentration in a thermal–hydraulic computer code.