无振荡可压缩两相流切割网格方法及其在激波诱导气泡塌陷中的应用研究

This project focuses on the two-dimensional cut-cell method, which is of high order, high resolution of the interface and free of pressure oscillation near the interface, for compressible two-phase flow. This cut-cell method will be applied to the tiny bubble collapse induced by weak shock. The following research topics can be found in this study: 1. The coupling process of the cut-cell method and the level-set method will be analyzed to seek the cause for the pressure oscillation near the interface and the method to suppress the pressure oscillation will be proposed. 2. The mass conservation of the cut-cell method will be improved in this new method compared with the old one. 3. The discretization scheme for the interfacial jump condition for flow with viscosity, thermal conduction, surface tension and phase change will be proposed. 4. The code of cut-cell method will be constructed with the help of PARAMESH, which is an open source software with adaptive mesh and MPI technique. 5. The cut-cell method will be validated by the classical benchmark problems and the parameter space in which this code adapts will be verified. 6. The cut-cell method with the full NS equation and phase transition will be applied to the collapse of the tiny bubble induced by weak shock. The effects of the viscosity, thermal conduction, surface tension and phase transition on the jet formation, bubble dynamics and wave structures will be analyzed. This study is about the cutting-edge research on sharp interface method and its application in the compressible two-phase flow, which is of great value in this field.

本项目针对可压缩两相流，开展高精度、高界面分辨率、无界面压力振荡的二维切割网格方法研究，并采用该方法开展弱激波诱导的微型气泡塌陷的研究。研究内容主要如下：分析切割网格方法与 Level-set 方法的耦合方式，寻找切割网格方法中压力振荡产生的原因并提出克服该振荡的方法；改善切割网格方法中各相介质的质量守恒性；提出包含粘性、热传导、表面张力和相变时的界面间断条件的离散方法，通过经典算例，逐项验证粘性、热传导、表面张力和相变各项，并确认程序适应的参数范围；发展基于开源网格自适应的并行程序 PARAMESH 的切割网格程序；使用全 NS 方程在考虑界面相变的情况下模拟水中弱激波诱导的微型气泡塌陷的过程，并分析粘性、热传导、表面张力和相变对射流形成、气泡演化、波系结构等的影响。该项目研究是关于可压缩两相流的尖锐界面数值方法及应用的前沿课题，具有重要的学术价值。

本项目针对可压缩两相流开展高精度、高界面分辨率、无界面压力振荡的二维切割网格方法研究，并采用该方法开展弱激波诱导的微型气泡塌陷中的研究。研究内容主要如下：分析了切割网格方法中压力振荡产生的原因并提出一种混合方法克服该振荡；提出包含粘性、热传导、表面张力和相变时的界面间断条件的离散方法；发展基于开源自适应、并行程序PARAMESH的切割网格程序；模拟了水中弱激波诱导的微型气泡塌陷的过程，并分析了相应的物理过程。.该项目研究发展了目前前沿的两相流切割网格数值方法，解决了其在界面拓扑结构改变时的压力振荡的问题。该方法在弱激波诱导水中气泡塌陷的应用研究发现计算结果同前人实验的发现的射流现象一致，回答了前人发现的数值模拟和实验不一致的原因可能是文献中数值模拟方法和参数不合适造成的。通过该项目建立的两相流模拟程序，为将来进一步研究两相流的其他物理问题打下基础。

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