Analysis of three-dimensional numerical simulation methods for turbulent flow past circular cylinder

Studying the influences of a turbulence simulation method on the accuracy of the three dimensional numerical simulation of the turbulent flow past a circular cylinder, this study is made in a subcritical region(Re=3900) by using κ-ω model, SST model, and large eddy simulation (LES), which are included in Reynolds average Navier-Stokes(RANS) . Analyses of the stress distribution on the surface of the cylinder, the time average velocity characteristics of the flow field and the instantaneous vorticity distribution of the flow field behind the cylinder have been done in the study. The analysis results show that the negative pressure difference on the surface of the cylinder, which is of opposite direction to the velocity when flow passes a circular cylinder, separates the fluid from the surface of the cylinder and causes unstable periodic turbulent vortex shedding, which resulted to the periodic fluctuation of the lift force on the cylindrical surface and a backflow zone behind the cylinder. Moreover, the simulation effect of the LES method on the stress distribution on the cylindrical surface and a time average velocity characteristics of the flow field are superior to κ-ω model and SST model. Compared with the simulation results of immersed boundary method used by DU Yuan-zheng, the simulation precision of the LES method also has greater improvement. Then based on the analysis of the iso-contour maps of the vorticity magnitude of the flow field and comparing them with the existing simulation results, the LES method can not only depict the periodic shedding vortices as a whole, but also describe the complex small scale turbulent vortex at different positions of the flow field meticulously. And the scale of the separated free-shear layers and the crimpness of the vortex are more in line with the characteristics of the turbulent vortex shedding. Finally, it came to the conclusion that the simulation effect of the LES method for the turbulent flow is relatively better than that of the κ-ω model and SST model in the subcritical region.