Homogeneous wall boundary condition for oscillatory flow in slotted tunnels

Abstract

Abstract The aerodynamic interference between oscillating models and the walls of slotted windtunnels is controlled by the homogeneous wall boundary condition, which has hitherto been uncertain. In this report a new homogeneous boundary condition for slotted tunnels is suggested which incorporates the important effects of plenum chamber depth and slot parameter.In particular, this new boundary condition controls the transverse resonance frequencies of the tunnel, which represent a severe form of wall interference. Hence a comparison of measured resonance frequencies with predictions based on such a boundary condition provides a good test of its correctness.The new homogeneous boundary condition complements that obtained previously for a perforated tunnel and is essentially similar in character. The boundary condition is applicable to oscillatory flows at frequencies ranging from quasi-steady values to multiples of the first resonance frequency.