Influence of Reynolds number on coherent structure, flow transition, and evolution of the plane jet

抄録

In the present study, the flow characteristics of a spatially evolving plane jet are investigated, focusing on the dynamics of coherent structure (CS), flow transition, and evolution. Instantaneous and statistical properties obtained by direct numerical simulation (DNS) are discussed noting the influence of the Reynolds number, by analyzing the velocity and scalar fields. It is discovered that the plane jet is clearly dependent on the Reynolds number, especially in the near field. The evolution and scale of CS have a strong dependence on the Reynolds number, which shows significant effects on the transport of the momentum and scalar. The increase of the Reynolds number develops a more contorted interface between the ambient fluid and plane jet, with a smaller scale. A moderate Reynolds number is a good condition for the study of the transition from a laminar jet to a turbulent jet in detail. The results show that, because of a low Reynolds number, the growth of two initial shear layers at the jet boundary is accelerated and the velocity fluctuation is advanced from two-dimensional to three-dimensional. Furthermore, the Reynolds number dependency of the plane jet is more significant on the condition of low Reynolds number.