基于界面概率近似的气液两相流界面多尺度问题计算方法

Computability menthod research on multi-scale interface problems in gas-liquid two-phase flow is carried out. Eulerian two-fluid model with an interface probability approximation method (TFM-IPAM) is proposed. It uses a high precision scheme named compressive interface capturing scheme for arbitrary meshes (CICSAM) to control interface numeral diffusion, and uses a probability approximation method to make uncertainty interfaces caused by unavoidable numerical diffusion into certainty interfaces with the probabilistic sense. The process of the interface identification is realized by the Heaviside function in the level-set method, and then the hierarchical processing for different-scales interfaces is achieved. On this basis, the first level will carry out sensitivity analysis, designed to define important factors of models and parameters. The second level will be to compare calculation accuracy and computational efficiency with the aim of assessing the technical level of TFM-IPAM relative to foreign research models/methods. The third level will develop and refine computational method to achieve the simultaneous solution of interface across the scale in mixed flow and interface scale distribution in discrete flow. The main innovations are as follows: (a) distinguish the computational dilemma of multi-scale interface problem in gas-liquid two-phase flow, and fill the domestic lack of understanding and research on this problem; (b) provide a simple and effective engineering computability method for multi-scale problem of gas-liquid interface; (c) fully evaluate the maturity of computability method and provide support for its transformation to engineering applications.

开展气液两相流界面多尺度问题计算方法研究，提出基于界面概率近似方法的欧拉双流体模型（TFM-IPAM）。采用高精度压缩差分格式控制界面数值扩散，采用概率近似方法将由数值扩散造成的不确定界面转化为概率上确定的界面，基于水平集方法中的海维塞德函数实现界面识别过程，从而实现大小尺度界面的层次化处理。在此基础上，第一层次将开展灵敏性分析，旨在界定模型及参数的重要影响因素；第二层次，将开展计算方法精度和效率的优劣对比，旨在评估相对于国外研究模型/方法的技术水平；第三层次，将发展和完善计算方法，旨在实现混合流界面跨尺度性和离散流界面尺度分布性的同时求解。主要创新之处在于：（a）辨析气液两相流界面多尺度问题可计算性困境，填补国内对气液界面多尺度问题可计算性认识与研究的不足；（b）为气液界面多尺度问题提供一种简单有效的工程计算方法；（c）全面系统的评价计算方法的成熟度，为技术的工程应用转化提供支撑。

在航空航天、核工业、化工领域、生物系统以及自然现象中，气液两相流广泛存在，而且无论是重力条件还是微重力条件，在瞬态时间中复杂多变的气液两相流界面结构具有宽广的空间尺度范围。气液两相流界面多尺度计算问题是近年来国内外气液两相流领域的研究焦点之一。针对气液两相流界面多尺度计算问题，基于界面概率近似科学思想，课题组提出并完善了TFM-IPAM嵌入式仿真模型，提出并发展了DPM-VOF耦合式仿真模型。计算方法TFM-IPAM通过基础验证，证明TFM-IPAM的有效性、计算精度、计算效率以及计算方法适应性。计算方法TFM-IPAM和DPM-VOF得到发展完善，逐步形成基于界面概率近似的、以TFM-IPAM和DPM-VOF为支撑的气液两相流界面多尺度问题计算方法体系。计算方法工程应用效果显著，基本解决了航空航天水气分离、飞机/发动机防除冰等过程中气液两相流界面多尺度问题仿真难题。基于界面概率近似的、以TFM-IPAM和DPM-VOF为支撑的气液两相流界面多尺度问题计算方法体系，在气液两相流数值模拟方面具有较好的学术价值，在航空航天水气分离技术和飞机/发动机防除冰技术等方面具有较高的工程应用价值。