Using inclined walls to control the bottom shear stress distribution in an annular flume

This study proposes a method to alter secondary flow pattern in a rotating annulus flume and obtain a resulting uniform bottom shear stress distribution along the radial direction by changing the shape of the channel cross section. Two or three wall angles, except for the bottom wall angle, are simultaneously changed up to 25° for different cross-sectional shapes. The flow characteristics in the channel are analyzed using the computational fluid dynamics technique to find the most effective configuration of the walls, including the rotating top ring. The results show that the bottom shear stress decreases and becomes uniform as the outer wall and the top ring angles increase. In the case of the inner wall, the wall angle has little effect on the bottom shear stress. The stress distribution is most uniform when the top ring, the outer wall, and the inner wall angles are 25, 25, and 5°, respectively.