FLOW IN THE MISALIGNED CONE-AND-PLATE RHEOMETER

The effects of small misalignment in the cone-and-plate rheometer on the flow of a Newtonian fluid, an upper-convected Maxwell fluid, and a White-Metzner fluid are examined in detail. The method of domain perturbation and the lubrication approximation are employed to calculate velocity and stress profiles to first order in the misalignment parameter epsilon. Results for the Newtonian fluid show symmetric velocity and stress profiles around the plane at the widest gap. The two elastic fluids studied exhibit asymmetry in their velocity and stress profiles caused by fluid memory effects. Misalignment effects on torque and thrust measurements in the cone and plate are also discussed, and results are compared with a similar calculation made for flow in the journal bearing.