要約

Direct numerical simulation data have been analysed to investigate the effect of uniform wall blowing and suction on the near-wall turbulence structure. Blowing is applied at the lower wall of the channel and suction at the upper wall, respectively. The modulation of the near-wall anisotropy with uniform wall blowing and suction is examined in terms of the anisotropy invariant map (AIM) for the Reynolds stress anisotropy tensor. It is found that blowing makes the flow more isotropic, enhancing transverse (v^'2 and w^'2) components of velocity fluctuations significantly. A significant increase in the anisotropy of the near-wall region is found in the suction case, making the flow approach towards a one-component state in the anisotropy invariant map. The AIM analysis indicates that the relaxation processes of the anisotropy of the near-wall turbulence are different for the blowing and suction cases.