A COMPUTATIONAL STUDY OF JOINT EFFECTS OF TRANSVERSE-SHEAR AND STREAMWISE ACCELERATION ON 3-DIMENSIONAL BOUNDARY-LAYERS

An initially two-dimensional turbulent boundary layer was subjected si multaneously to a transverse shear, imposed by a moving wall, and a st rong streamwise acceleration, and the joint effects were studied compu tationally by applying a second-moment closure model with new low Re n umber and wall proximity modifications. The model was previously verif ied in the computation of several two-dimensional thin shear flows, in cluding the cases in which each of the two considered external effects were present separately. The comparison with the available, though mo dest, experimental results shows good agreement. The computations show a dominant effect of the imposed transverse shear manifested in a lar ge turbulence production in the initial region of the three-dimensiona l boundary layer, but the strong acceleration subsequently becomes dom inant over the flow and damps the turbulence, leading to eventual rela minarization. The dynamics of the turbulence response, which is strong ly dependent on the relation between the magnitudes of the two counter acting effects, was well reproduced by the applied model.