The two-dimensional and three-dimensional turbulent reattaching shear layer behind the rearward-facing step was studied experimentally for the effect of the streamwise pressure gradient to the reattachment length, the wall static pressure, the mean flow field, and it's mean static pressure distribution. The governing streamwise positive and negative pressure gradient are controlled by the deflection of the wind tunnel roof. In the two-dimensional flow range the pressure gradient effect on the reattachment length was not uniquely dominant in contrast to the three-dimensional flow, the pressure gradient v.s. reattachment length is given by a constant slope. The similarity curve for the wall static pressure only exists in the region of the recirculating flow independent of the pressure gradient and the aspect ratio. The streamwise, cross-streamwise flow profile and the mean static pressure show the strong mixing effect in the outer layer of the free stream.
