Inertia Effects on the Flow of Viscoplastic Fluids Through an Abrupt Contraction
Volume Title: 1
School of Mechanical Engineering, Tehran University, Tehran, Iran
This paper is concerned primarily with the effects of inertia (Reynolds number) on the laminar flow of a non-Newtonian viscoplastic fluid through a sudden contraction in the planar and axisymmetric geometries. The influence of Reynolds number on the structure of the flow and pressure losses is studied using a numerical approach. The radius of the rigid moving zone is always unchanged for the different Re, but the downstream rigid moving zone is pushed away and it will vanish at Re=303. Inertia and yield stress act in opposite ways. When Re increases, pressure loss due to the singularity decreases. On the contrary, as Bingham number increases, the pressure loss increases significantly. Moreover, a comparison between pressure drops in sudden expansion and abrupt contraction has been performed. The pressure loss due to the sudden expansion is higher than contraction (55%) until Bi= 100, in which they reach the same value of 2.8. Finally, the provided numerical results are validated by available experimental data.