Abstract Thermally induced density wave instability (DWI) (Type-II) is an important phenomenon for two-phase flow industrial systems. Developing numerical tools and methods for the prediction of the DWI boundary is of importance in the design and safety of nuclear reactors. With the advent of computational fluid dynamics (CFD) in nuclear safety analysis, it is important to first verify the CFD results against existing theory and validate them with experimental data. In this work, a CFD two-fluid model (TFM) for DWI was implemented and verified against the theory of Ishii (1971). Closure relations were selected to approach the homogeneous equilibrium flow model. A steady-state verification of the model was carried out first. Then, dynamic verification was performed. Predictions of the stability boundary and the frequency of oscillations are in a good agreement with the theory. This study further verifies the dynamic capability of TFM CFD.

中文翻译：

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CFD双流体模型密度波不稳定性验证

摘要 热致密度波不稳定性（DWI）（II 型）是两相流工业系统的重要现象。开发用于预测 DWI 边界的数值工具和方法对于核反应堆的设计和安全具有重要意义。随着核安全分析中计算流体动力学 (CFD) 的出现，首先根据现有理论验证 CFD 结果并用实验数据对其进行验证非常重要。在这项工作中，针对 DWI 的 CFD 双流体模型 (TFM) 被实施并根据 Ishii (1971) 的理论进行了验证。选择闭合关系以接近均匀平衡流动模型。首先对模型进行稳态验证。然后进行动态验证。稳定性边界和振荡频率的预测与理论非常吻合。本研究进一步验证了 TFM CFD 的动态能力。