The interfacial area concentration is an important parameter to characterize the interfacial
transport of mass, momentum and energy. The dynamic modeling approach of interfacial area, namely,
the Interfacial Area Transport Equation (IATE) is thus indispensable for an accurate prediction of twophase
flows using the two-fluid model. This article reviews the theoretical development of the IATE
from two aspects: formulation of the transport equation and modeling of the closures. The first
approach to arrive at the IATE is based on the statistical description of a large number of particles using
the Boltzmann transport equation. This approach is straightforward to obtain the macroscopic equation
of the interfacial area concentration. However, for flows with continuous interface such as annular flow,
one has to resort to the second approach, the local instantaneous formulation to derive the macroscopic
transport equation. The source and sink terms in the IATE are required to close the problem and they
are divided into volume change term, phase change term and particle interaction term. Details on
formulating IATE using both approaches and modeling of the closures are discussed.
Keywords: Multiphase flow, two-fluid model, interfacial area concentration, interfacial area transport
equation, bubble interaction mechanism.
