密度极值流体Poiseuille-Rayleigh-Bénard对流稳定性及耗散结构研究

由于Poiseuille-Rayleigh-Bénard(P-R-B)对流耗散结构的多样性及演变过程的复杂性，P-R-B对流一直是研究非平衡条件下耗散结构的形成及转变的经典模型，也一直是国际学术界研究热点之一。与常规流体相比，密度极值流体P-R-B对流耗散结构更加丰富、演变规律也更加复杂，而目前这方面的研究还是一片空白。本项目以水平矩形流道内密度极值流体P-R-B对流为研究对象，采用稳定性分析、数值模拟和实验观测相结合的方法，确定P-R-B对流发生的临界条件，获取各种可能的P-R-B对流流型结构及其演变规律；确定各种流型结构稳定存在范围及失稳临界条件，揭示Poiseuille流动和R-B对流耦合机制；寻找调控P-R-B对流流型结构及其演变过程的有效方法，分析流型结构与传热性能间的协同关系。本项目对于发展复杂流体流动非平衡热动力学耗散结构理论、拓展P-R-B对流研究领域具有重要科学意义。

Due to the diversity of the dissipative structures and the complexity of the transition processes of the flow patterns in Poiseuille-Rayleigh-Bénard (P-R-B) convection, it has been a classic model for the study of the formation and transition of the dissipative structure under the nonequilibrium thermodynamics condition, and has been one of the hot spots in the international academic community. Compared with the conventional fluids, P-R-B convection of fluids with the density extremum has more abundant flow pattern structures, and it is more difficult to determine the transition process among flow patterns. However, the research in this field is still blank. Aiming at P-R-B convection of the density extreme fluids in the horizontal channel with rectangular cross-section, this project studies multiplicity of flow pattern structures and complexity of flow pattern transitions by combining the stability analysis, numerical simulation and experimental observation. First, the critical conditions of P-R-B convection appearance are determined and various possible flow patterns and their evolutions are explored very carefully. Then, the stable existence range and destabilizing critical conditions of various flow pattern structures are determined and the coupling mechanism of Poiseuille flow and R-B convection is revealed. Furthermore, the measures to regulate and control the flow pattern structure of P-R-B convection and its evolution process are found, and the synergistic relationship between flow pattern structure and heat transfer performance is analyzed. This project is of great scientific significance for the development of the non-equilibrium thermodynamic dissipative structure theory on the complex fluid flow and the extension of the research field of P-R-B convection.