The logical design method of Owen & Zienkiewicz (1957), for the generation of linear shear flow, is successfully applied to the case of symmetrical velocity profiles in a two-dimensional duct. Shear parameters as high as 0·8 (corresponding to $\hat{V}| \overline {V} = 1\cdot4$) are obtained experimentally. Some slight modification to the theoretical grid spacing is required because of the non-uniformity of the upstream flow.

The decay of the profiles is confined to that due to the developing boundary layer and to the breakdown of the physically impossible condition at the centre, where symmetry implies a change in sign of the uniform shear.