The new flux representation of the two-fluid model of two-phase flow, where the mixture is described in terms of the volumetric and drift fluxes, is currently the most consistent formulation to treat the inertial coupling between phases. In this representation, the dynamics of the relative motion between phases is revealed as a non-linear wave propagation equation. It is shown that the character and stability of this equation is determined by the balance between the inertial coupling and the interfacial drag. A novel stability criterion is derived that can be used to assess the interfacial closure laws and as a tool to determine the conditions under which a drift-flux correlation is stable. A family of inertial coupling functions for vertical two-phase flow, based on topologies of bubble's vortical wakes, is derived and the corresponding coupling parameters are assessed using available experimental data. The resulting stability maps reveal the occurrence of an unstable region at intermediate void fractions bound by a bistable condition at low and high void fractions, which can be associated with the slug flow-pattern regime.

中文翻译：

---

惯性耦合在两相流二流体模型中的重要性

两相流的双流体模型的新通量表示，其中混合物以体积通量和漂移通量来描述，是目前处理相间惯性耦合的最一致的公式。在这种表示中，相间相对运动的动力学被揭示为非线性波传播方程。结果表明，该方程的性质和稳定性取决于惯性耦合和界面阻力之间的平衡。推导了一种新颖的稳定性准则，可用于评估界面闭合定律并作为确定漂移-通量相关性稳定的条件的工具。基于气泡涡旋尾流的拓扑结构，推导了一系列垂直两相流的惯性耦合函数，并使用可用的实验数据评估了相应的耦合参数。所得的稳定性图揭示了在低空隙率和高空隙率下受双稳态条件限制的中间空隙率处出现不稳定区域，这可能与段塞流模式相关。