Effects of pressure-gradient on turbulent counter-gradient transport
压力梯度对湍流逆梯度输运的影响

By using Reynolds Stress Closure Model (RSM) and k-e Model, the turbulent field of wing flow is numerically simulated. In most practical situations, flows with changing pressure gradient are familiar, these pressure gradients may induce strong modifications of turbulent structure, accordingly, affect the diffusion and transportation process of turbulence. The effects of pressure gradient on counter-gradient transport phenomena are studied. The computational results show that RSM model can describe the CGT phenomena while k-e model cannot. Negative turbulent energy production appears in the result of RSM, but it behaves differently with CGT: it gradually shrinks until the position of the wing central part is reached, where it vanishes; while the CGT region exists all along. This fact shows that CGT phenomena is more general than negative turbulent energy production. The pressure gradient takes an important effect on the region of negative turbulent energy production and counter-gradient transport. In the CGT region, the relation between turbulent Reynolds stress and mean velocity gradient is nonlinear.