Viscoplastic Fluid Flows Through An Abrupt Contraction

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#