Using CFD To Understand How Flow Patterns Affect Retention of Cell-Sized Particles in a Tubular Bowl Centrifuge

Abstract

Sigma theory is commonly used to predict the conditions that result in half of the entering particles being retained within a continuous-flow centrifuge. In this research, a 2D computational fluid dynamics (CFD) model of flow through a tubular bowl centrifuge (Sharples, 5 cm radius) was developed with Fluent software. A volume-of-fluid (VOF) approach was used for most of the simulations to track the motion of the liquid and gas phases, because the location of the gas/liquid interface depends on the centrifuge operating conditions. The CFD results indicate that the assumptions of plug flow and rigid body motion, which are fundamental assumptions of Sigma theory, were not valid for the conditions tested (700 < Rez < 3500 and 1000 < speed (rpm) < 3000). The average interfacial axial velocities (Viz) were 6−18 times greater than the plug-flow velocity (Vpf), and the average interfacial swirl velocities (Viθ) were 0.12−0.41 of that corresponding to rigid body motion (Vrbm). Despite these differences, the CFD r...