Study on boundary layer in a rotating channel

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The objective of project is to make clear the effects of Coriolis force on the developing two-dimensional boundary layer on trailing and leading side walls of a rotating channel, on the turbulent wake behind a fixed spanwise/transverse circular cylinder, and to offer many data on time-mean and turbulent quantities which are desirable in numer-ical simulation of rotating turbulent boundary layer. Thus, a rotating wind tunnel was designed, and quantitative experiments were performed.The experimental results indicate that the development of boundary layer on the leading side in rotating channel is promoted and suppressed on the trailing side. Two-dimensionality of the boundary layer is preserved on the trailing side, while three-dimensionality corresponding to Taylor-Goertler type longitudinal vortices is generated on the leading side. At higher rotation number, the phenomenon of relaminarization was observed on the trailing side. Reynolds stresses data agreed qualitatively with that predicted from the Reynolds stress equations with rotation.In a rotating wake behind a fixed spanwise cylinder, breakdown of shed vortices occurs at lower Reynolds number than in a non-rotating wake because of a transverse velocity gradient of primary flow and a flow instability due to instantaneous coriolis force. For a turbulent wake behind a low aspect ratio cylinder located spanwise, profiles of mean velocity and turbulence intensity are not symmetrical about the wake centerline. The wake is a very complex three-dimensional flow because of a three-dimensional separation around a cylinder and a secondary flow in a boundary layer on the top and bottom walls of a rotating channel.