Impingement of a confined axisymmetric jet on smooth and rough flat plates: near wall behaviour

This paper investigates the influence of some governing parameters on the near wall characteristics of a circular impinging jet onto smooth and rough flat plates. Laser Doppler anemometry (LDA) and particle image velocimetry (PIV) are used to characterize the mean and turbulent fields including the wall shear stress. The experiments were conducted at one nozzle-to-plate space and Reynolds number of 35,000. The work discusses in particular a near wall parametrization scheme for the mean velocity profile that resorts to a scaling procedure based on the stream-wise evolution of the flow characterized by its maximum velocity.