Lubrication of journal bearings by shear thinning lubricants using different constitutive models.

The lubrication of hydrodynamic journal bearings using shear thinning fluids is investigated analytically by comparing three different constitutive models. Whilst journal bearings have been in use for a long time, they are still fundamental components of the most advanced mechanical systems, and will remain so for a long time to come. In particular, the modified Reynolds equations for the power-law (Ostwald-de Waele), the Carreau and the Cross models were derived based on the perturbation method. The three models were used to calculate the pressure distribution and the load carrying capacity, and their results were compared and discussed. It is shown that at high shear rates (i.e., high shaft speeds) the Carreau and Cross models, which better describe the rheology of shear-thinning fluids, yield higher magnitudes of the pressure than the power-law model, while at low shear rates the three models are in better agreement. [ABSTRACT FROM AUTHOR]