Fluid inertia effects on a Controlled Stress Rheometer in its oscillatory mode

Abstract

This paper is concerned with the effect of fluid inertia on experimental oscillatory stress data taken from a Controlled Stress Rheometer. A linear viscoelastic theory is developed which includes the effect of fluid inertia for cone and plate, parallel plate and concentric cylinder geometries. This theory is used to interpret dynamic data for both a slightly elastic and a highly viscoelastic fluid. It is shown that intertial effects are very small for both a cone and plate and parallel plate geometries. Inertial effects, however, can be important in the concentric cylinder geometry.