Viscoplastic Fluid Flows Through an Abrupt Contraction
Volume Title: 1
1Mechanical Engineering Department, Tehran University, Tehran, Iran
2School of Mechanical Engineering, Tehran University, Tehran, Iran
Numerical simulations were performed for the creeping flow of a yield-stress fluid through a sudden contraction using the Herschel-Bulkley model with a Papanastasiou's modification. The influence of yield-stress and contraction ratio values on the structure of the flow was investigated. All the simulations were carried out for 2D, 3D, and axisymmetric geometries. The detailed structure of flow shows two rigid zones, one located at the corner of the contraction (rigid static zone) and one located close to the center-line of the channel (rigid moving zone). When yield stress increases, the size of the rigid dead zones increases significantly. Moreover, the pressure losses are given with yield stress, contraction ratio, and geometry. It is seen that 2D and axisymmetric models are not accurate indicating the need to account for the cross-section shape. Finally, the numerical results are compared with the available numerical and experimental data.