Modulation of Near-Wall Turbulence Structure with Wall Blowing and Suction

The effects of wall blowing and suction on a fully developed, equilibrium turbulent channel flow are studied numerically. Direct numerical simulation data are analyzed to investigate the modulation of near-wall turbu-lence anisotropy after the sudden application of wall blowing and suction. The effects on the near-wall turbu-lence structure are examined in terms of the asymptotic near-wall behavior of various turbulence quantities and the turbulence anisotropy. It is found that blowing makes the near-wall flow more isotropic and enhances the transverse (v ′ and w′) components of velocity fluctuations. A significant increase in the anisotropy of the near-wall region is found in the suction case. The anisotropy invariant map for the Reynolds stress anisotropy tensor indicates that the relaxation processes of the anisotropy of the near-wall turbulence are different for the blowing and suction cases, respectively. The response of the flow to the sudden application of wall blowing and suction occurs earlier for blowing than for suction, although there is a delayed response in both cases. Nomenclature bi j = Reynolds stress anisotropy tensor, u′i u j/2k − δi j/3 F = invariant function, 1 + 9II + 27III