Title: A study of near-wall flow field of oscillating turbulent channel flow. 1st Report. Time mean and phase-averaged velocity.
Abstract: Hot-wire measurements of the near-wall velocity profile in oscillating turbulent channel flows were performed at the intermediate frequency range, where wall shear, inertia and pressure gradient are all important but the frequency is much smaller than the bursting frequency. Viscous sublayer thickness, wall shear stress and the phase averaged wall law were examined. The phase averaged velocity profile in the near-wall region was found to obey the steady-state wall law if the wall coordinate was defined using the phase-averaged friction velocity, although the amplitude of the velocity oscillation changes from the laminar-Stokes profile to the quasi-steady turbulent profile with increasing non-dimensional Stokes thickness.