Exploration of Gas-liquid Flow Mixing Region for the Purpose of Drift-flux Model Enhancement

The Drift-Flux model (DFM) is a powerful reduce order model that can be applied to gas-liquid flows. As applied to a one dimensional internal flow the model requires specification of two parameters: $C_{0}$ (distribution parameter) and $v_{s}$ (weighted mean drift velocity). It is the goal of the current study to develop a Drift-Flux model appropriate for mixing regions in pipe flows for a range of gas-liquid flow parameters that addresses both steady and transient flows. This study focuses on high fidelity simulations useful for the determination of both $C_{0}$ and $v_{s}$. A wide range of both transient and steady flow conditions is used (inlet parameters and fluid properties). The result is a range of two phase flow conditions, or flow map regimes, within the mixing region. For each set of conditions results are used to identify values of $C_{0}$ and $v_{s}$. Functional relationships are then found to map these parameters to the flow map regimes. The extent and range of the functional relationships allows for a robust set of conditions that can be utilized in the Drift-Flux model. Using these results comparisons are made with existing functional forms of $C_{0}$ and $v_{s}$ to help identify the sensitivity to the transient conditions of mixing.