Articles techniques et présentations

In certain cases, the accuracy of measurements with a rotational rheometer can be influenced by inefficient thermal management, by the heat generated in the sample, or by rod-climbing due to the Weissenberg effect. We investigate the effect of these phenomena with simulations in COMSOL Multiphysics®. Our model is based on the axial symmetric (2D) formulation of the two-phase flow with the level-set method, including swirl velocity. The rheological constitutive equation is implemented in general PDE mode, coupled to the flow problem. Here we use an upper-convected nonlinear Maxwell model with shear-thinning viscosity, which is based on a lumped parameter model derived from standard rheometry measurements. The model is completed by coupling a heat conduction problem for the simulated measuring device.