Interfacial forces used in two-phase flow numerical simulation

High fidelity 3D computational simulation for gas-liquid two-phase flow is getting important to simulate various thermal-hydraulic phenomena in nuclear related components. Single-phase computational simulation techniques have reached to a certain level of reasonable prediction accuracy for the purposes of designs and performance analyses of industrial equipment. However, two-phase computational simulation techniques have not reached to the level of reliable prediction due mainly to the difficulty in the modeling of interfacial transfer terms. Accurate modeling of the interfacial forces including the interfacial area modeling is one of the keys to predict the distribution of gas phase in various two-phase flow systems successfully. This paper is aiming at reviewing the interfacial force modeling including recent advance of the interfacial area transport equation. This paper discusses the frame-work of bubble-wall collision force which is potentially used in place of the wall lubrication force applicable for laminar flow. This paper also discusses the frame-work of the bubble collision force considering the effect of the bubble coalescence on the bubble collision frequency. The review of existing interfacial force models including newly developed bubble-wall collision force and recent advance of the interfacial area transport equation offers the most advanced knowledge of constitutive equations necessary for improving the predictive capability of the two-phase flow computational simulation codes.