可压缩稠密与稀薄多相流的欧拉-拉格朗日耦合算法研究

Metal material ejection and mixing with gas in the implosion process of engineering geometry-convergence equipment is a typical compressible multiscale multiphase flow, where both dense and dilute dispersed phases coexist under shock loading. Until now, the modeling and simulation of this complex multiphase flow are still an open problem. This project will develop a well-posed governing equation based on Eulerian-Lagrangian(E-L) framework for both dense and dilute regimes; propose a unified discrete particle model for four-way interactions among gas and particle phases; and develop robust high-resolution numerical schemes for the well-posed multiphase model. This project will develop a combined Eulerian-Eulerian/Eulerian-Lagrangian (E-E/E-L) method for dense- and dilute-phase coexisting flows with moving interfaces, and extend the hybrid method to multi-material flows with the general equation of state and elasto-plastic constitutive relation. This project will develop a large-scale parallel software for high performance computing based on based on multiscale adaptive mesh refinement (AMR) algorithm, verify and validate (V&V) the correctness and accuracy of the physical model, numerical method and software, and study the uncertainty quantification (UQ) of the model and algorithms with important parameters. This project will build the ability to give some preliminary predictions to high-speed compressible multiphase flow with both dense and dilute disperse regimes in engineering physics problems. This research not only has important value for the complex multi-material multiphase flow in the weapon physics, but also has principle scientific significance to the compressible multiphase hydrodynamics (CMH) and computational fluid dynamics (CFD) due to its frontier nature.

工程装置内爆汇聚压缩过程中金属材料喷射并与气体混合的现象是典型的冲击波作用下稠密与稀薄离散相共存的可压缩多尺度多相流动。目前这类复杂流动的物理建模和计算方法还很不完善。本项目基于欧拉-拉格朗日框架发展稠密与稀薄共存气粒两相可压缩流动的适定控制方程，建立可统一处理四向耦合多相流动各相间相互作用的离散颗粒模型，并发展相应的高分辨率健壮数值格式；发展包含运动界面的稠密与稀薄共存可压缩多相流的欧拉-欧拉/欧拉-拉格朗日耦合计算方法，并推广到基于一般状态方程与弹塑性本构关系的多介质多相流动；研制基于多尺度网格自适应算法的大规模并行计算程序，验证和确认模型算法及程序的有效性与准确度，并评估和量化不确定度范围；初步实现工程物理中稠密与稀薄共存的高速可压缩多相流体力学问题的模拟预测。本研究不仅对武器物理中复杂介质多相流动等有重要价值，而且也是可压缩多相流体力学和计算流体力学的前沿课题，有重要的科学意义。

工程装置内爆汇聚压缩过程中金属材料喷射并与气体混合的现象是典型的冲击波作用下稠密与稀薄离散相共存的可压缩多尺度多相流动。目前这类复杂流动的物理建模和计算方法还很不完善。本项目 (1) 对于稠密与稀薄共存的多流态气粒两相可压缩流动，基于MP-PIC思想的发展了可统一处理四向耦合多相流动各相间相互作用的离散颗粒模型及相应的高精度计算方法。(2) 对于包含运动界面的稠密与稀薄共存可压缩多相流，在基于流固耦合框架和虚拟流体算法(Ghost-Fluid Method)的基础上，发展了多介质欧拉-欧拉(E-E)以及欧拉-拉格朗日(E-L)耦合计算方法，相关气粒固耦合算法尚未有报道。(3) 基于国产结构网格自适应JASMIN框架，将上述多流态气粒两相可压缩流动的耦合欧拉-拉格朗日(C-E-L)计算方法进行了并行化，在国产自主cpu集群上500核50%以上并行加速比。(4) 针对弹塑性固体的超弹性模型，基于刚性气体状态方程及Mie-Grüneisen（MG）状态方程，发展了高精度/组分分界面无震荡的数值算法。(5) 建立了一套高精度的微喷颗粒场速度PDV频谱重构算法和程序；基于理论建模提出了一种直接从PDV频谱进行参数提取的新的频谱解读策略。其中气粒固多物理场耦合模拟程序和颗粒PDV速度频谱分析解读程序已经在工程应用中获得实际应用，主要用于工程设计的对比分析和验证工作。在本项目资助下，已在SCI 收录的国际期刊上发表学术论文5 篇。本项目研究不仅会促进可压缩多相流体力学和计算流体力学的理论研究水平，而且可为重要工程问题研究提供物理认识基础和数值支撑，同时在常规武器多相爆轰、火炮身管冲蚀磨损、先进固体火箭发动机、超燃冲压发动机、航天器大气层烧蚀防护、惯性约束聚变、及天体物理等领域也有重大应用价值。