Analysis and Measurement of Unsteady Flow in Curved Pipes

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(1) Three components of mean velocity have been measured in a square sectioned 90 degree bend of radius ratio 2.0 with upstream and downstream straight ducts under Reynolds number 40000. The bias of the axial flow and the intensity of the secondary flow were investigated from the upstream of the bend to the downstream.(2) A Reynolds stress model is applied to a fully-developed turbulent flow in a curved circular pipe. Numerical results are compared with the authors' experimental data. Computed velocity is in moderate agreement with the experimental results over the cross section.(3) Visualization was made of the secondary flow in the fullydeveloped region of a curved pipe under oscillatory laminar flow conditions; Womersley number 5.5 to 28 and oscillatory Dean number 40 to 500. The flow pattern, the velocity profile and the vortex center of the secondary flow were made clear.