SIMULATION OF NON-NEWTONIAN FLOW IN A HYDROCYCLONE

The results of a numerical simulation of a non-Newtonian flow of a she ar thinning fluid inside a hydrocyclone are presented. The fluids used were carboxy-methylcellulose polymer solutions whose rheological prop erties were described using a power law shear-rate dependence. This sy stem is a model analogue for drilling fluids. An axisymmetrical, lamin ar swirl flow was analysed by solving a set of conservation equations in which the air core radius was explicitly included, employing a surf ace-tension force balance equation. The results predicted a distinct d ifference in velocity distribution within the hydrocyclone between a s hear-thinning fluid compared to a simple Newtonian fluid. The predicte d non-Newtonian fluid velocity agreed well with independent flow and v elocity measurements obtained from Laser Doppler Anemometry. The thick ness of the vortex finder is shown to have a significant effect on the flow pattern in the hydrocyclone, and this is likely to affect the cl assification efficiency. This result has important implications for th e design and selection of hydrocyclones for handling non-Newtonian mix tures.