Abstract The accuracy of the Eulerian two-fluid model to solve dispersed and segregated multiphase flows was evaluated. Five air-water tests representing flow regimes commonly found in nuclear installations were considered: (a) bubbles ascending in a stagnation water column, (b) air-water upward flow crossing an obstacle in a vertical column, (c) liquid-liquid co-current horizontal flow, (d) air-water counter-current horizontal flow, and (e) air injection and swelling in the vertical water colu mn. The first four tests corresponded to steady-state benchmarks reported in the literature, and the last one was an experimental test proposed to assess the computational model under transient high void fraction flow. The five cases were simulated using the same set of interfacial force models in order to find one computational model suitable to solve all the regimes thanks to the use of a linear blending method to automatically switch the interfacial models accounting for the local rheology of the flow (drops in air, bubbles in water, segregated flow). The dispersed flow cases (cases a, b and e) were suitably modeled using the models proposed by Grace (drag), Tomiyama (lift), Frank (wall lubrication), and Burn (turbulent dispersion). On the other hand, the segregated systems (cases c and d) were solved using the drag model proposed by Marschall. Regarding turbulence, the κ - ω SST model was appropriated for both cases.

中文翻译：

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分散流和分离流的水-空气流两相模拟

摘要 评估了欧拉二流体模型求解分散和分离的多相流的准确性。考虑了代表核装置中常见流态的五项空气 - 水测试：（a）气泡在停滞水柱中上升，（b）空气 - 水向上流动穿过垂直柱中的障碍物，（c）液 - 液共- 水平流，(d) 空气-水逆流水平流，以及 (e) 垂直水柱中的空气注入和膨胀。前四项测试对应于文献中报道的稳态基准，最后一项是为评估瞬态高空隙率流动下的计算模型而提出的实验测试。这五种情况使用相同的界面力模型集进行模拟，以找到一个适合解决所有状态的计算模型，这要归功于使用线性混合方法自动切换考虑流动局部流变性的界面模型（空气中的液滴、水中的气泡、分离的流动）。使用 Grace（阻力）、Tomiyama（升力）、Frank（壁面润滑）和 Burn（湍流扩散）提出的模型对分散流情况（情况 a、b 和 e）进行了适当建模。另一方面，分离系统（情况 c 和 d）使用 Marschall 提出的阻力模型求解。关于湍流，κ - ω SST 模型适用于两种情况。