NON-NEWTONIAN FLOW BETWEEN CONCENTRIC CYLINDERS CALCULATED FROM THERMOPHYSICAL PROPERTIES OBTAINED FROM SIMULATIONS

A study of the Weissenberg effect (rod climbing in a stirred system) b ased on nonequilibrium molecular dynamics (NEMD) is reported. Simulati on results from a soft-sphere fluid are used to obtain a self-consiste nt free-surface profile of the fluid of finite compressibility undergo ing Couette flow between concentric cylinders. A numerical procedure i s then applied to calculate the height profile for a hypothetical flui d with thermophysical properties of the soft-sphere liquid and of a de nse colloidal suspension. The height profile calculated is identified with shear thickening and the forms of the viscometric functions. The maximum climb occurs between the cylinders rather than at the inner cy linder.