Direct numerical simulation of compressible effects on flat-plate turbulent boundary layer

Key words:  compressible effect  flat-plate turbulent boundary layer  direct numerical simulation  turbulent energy

Abstract:

A direct numerical simulation of a spatially evolving compressible flat-plate turbulent boundary layer with incoming Mach number Mx for 2. 25 was performed for solving three-dimensional compressible Navier-Stokes equations using high order compact finite difference schemes, through introducing a periodic blowing and suction disturbance on the upstream local wall. The turbulent statistics results agree well with the related theoretical and experimental data. The compressible effects on the characteristics of mean flow and production and dissipation of turbulent energy in flat-plate turbulent boundary layer flow were analyzed，and Morkovin's hypothesis comes into existence basically under the condition of MK for 2. 25. However, the results show that the ordered structures are different obviously on the effect of the compressibility. The action on different region for up-throwing and down-sweeping in the compressible turbulent boundary layer flow is different from that in the incompressible channel turbulent flow. The terms of pressure-dilatation and pressure-velocity can not be neglected near the wall, which leads to the production of sound and the restrained action to turbulent energy produced by compressibility effects. Further ,the situation of the sound pressure on the wall of the compressible flat-plate turbulence was presented, which shows that the source of noise produced by the pulsation pressure was inspired during the transitional progress with the evolving of the boundary layer flow.