Progress of the unified wave-particle methods for non-equilibrium flows from continuum to rarefied regimes

The predictions of the multiple-regime flows from continuum regime to free molecular regime are crucial for the aerodynamic design in a large number of engineering applications, such as the near-space craft, the ultra-low orbit spacecraft and the micro- electro-mechanical systems (MEMS). Since the essence of this multiple-regime problem is a complex system composed by different scales and mechanics, the modeling and numerical prediction of these multiple-regime flows are very challenging at both theoretical and practical levels. Moreover, the single flow field with multiple flow regimes will make the problem extremly complicated. Unfortunately, this typical flow field is very common in hypersonic application and important for the development of multiple-regime aerodynamics. On the other hand, both the constructions of the low density wind tunnel with high enthalpy and the high altitude flight experiment are also very challenging at the present stage. Therefore, the researches on the multiple- regime flows and the corresponding complex science hit a worldwide bottleneck. This paper reviews the breakthroughs in the computational methods for multiple-regime flows in the last ten years, which can be used as numerical experimental tools for studying the multiple-scale flow mechanism and providing data for aerodynamic designs and thermal protections. This paper focuses on the progress of the unified wave-particle methods established in recent years, which are proved to be both accurate and efficient for multiple-regime flows with extremly high speed. [Figure not available: see fulltext.].