Development of a turbulent boundary layer in a rotating square cross-section channel with relatively high local rotation parameter

The development of turbulent boundary layer in a rotating square cross-section straight channel were experimentally measured using hot wire in a new rotating facility. Measurements were conducted at four streamwise stations to study the development of turbulent boundary layer along the stream wise. The governing parameters of the boundary layer are local Reynolds number uτδ/ν and local rotation parameter Ων/uτ2 (uτ is the friction velocity, δ is the thickness of boundary layer, ν is the kinematic viscosity coefficient and Ω is the angular velocity of the channel, which is defined to be positive near the trailing side wall and negative near the leading side wall). The measurements are performed in the range of 199⩽uτδ/ν⩽367 and -0.0135⩽Ων/uτ2⩽0.0054 (these values correspond to u¯D/ν = 19,000 and 0⩽|Ω|D/u¯⩽0.362, here, u¯ means the cross-section averaged streamwise velocity, and D means the hydraulic diameter of the channel). Due to the relatively high local rotation parameter |Ω|ν/uτ2 on the leading side (up to 0.0135), some new phenomena were discovered, such as the critical rotation number phenomenon revealed in the variations of wall friction coefficient (the critical rotation number ranges from 0.145 to 0.362), the so-called relaminarization process near the leading side wall. Moreover, in high local rotation parameter cases, the lower limit of the Coriolis force influenced region is too close to the wall to be recognized with the traditional method, hence a new method to evaluate the influence of Coriolis force was proposed in the present work.