Calculation of Boundary Layers With Sudden Transverse Strain

Abstract

Modifications to a Reynolds stress closure are proposed in which the weighting of the two components of the pressure-strain correlation is adjusted: the turbulence part is increased to conform with measured rates of return to isotropy and the contribution from the mean-strain part is reduced. Consequential changes are then needed in the other closure assumptions. Their effect is to make the model more generally applicable and to improve predictions of turbulent flows in complex strain fields. The revised model is tested here against the measured response of axisymmetric boundary layers to suddenly imposed rotation. The wall region of this flow is resolved by means of wall functions where it is assumed that the directions of the shear stress and the mean-strain rate are coincident.