Local transitions in flow phenomena through packed beds identified by MRI



Magnetic resonance imaging (MRI) velocity measurement techniques are used to investigate flow of water and a glucose solution, of viscosity 3.89 × 10−3 Pa·s, within the interparticle space of a cylindrical packed bed of 5 mm diameter glass ballotini. The experiments were performed over a range of Reynolds numbers from 0.84 to 14.52, spanning the regime where inertial effects begin to play a significant role relative to viscous forces. A transition from creeping to inertial flow occurs in isolated pores at a local Reynolds number, defined for each pore within the interparticle space, of approximately 30. Despite this transition in flow behavior in some pores, the gross features of the flow pattern scale approximately with flow rate, which can be explained by considering the volume of the void space in which the flow is nearly stagnant as largely determining the pressure distribution within the bed.