THE STRUCTURE OF ZERO, FAVORABLE AND ADVERSE PRESSURE GRADIENT TURBULENT BOUNDARY LAYERS

The effects of pressure gradient on an initially zero-pressure-gradient turbulent boundary layer are investigated. We consider both adverse and favourable pressure gradients at matched Reynolds number as compared with the zero pressure gradient case. The data are also acquired using matched sensor parameters so that an unambiguous comparison can be made. The results show that energy increases throughout the turbulent boundary layer as the pressure gradient increases. It is also found that the large-scale motions are much more energetic for adverse pressure gradients compared with the other cases. The outer region of the flow appears most affected by the pressure gradient in this regard. The streak spacing in the near-wall viscous region is found to be unaffected by the pressure gradients, which is in contrast to other studies in the literature.