NON-NEWTONIAN LUBRICATION WITH THE 2ND-ORDER FLUID

In certain applications where the lubricant is subjected to rapidly ch anging conditions along its flowing path (such as an elastohydrodynami c contact), the inherently time dependent nature of the lubricant may be significant The simplest type of model to correctly account for suc h time dependence is the second-order fluid which is a systematic smal l departure from Newtonian behavior, involving higher order rate-of-ra te-of strain tensors. As in a companion paper using the Maxwell model, the formalities of applying such a model to thin film flow are emphas ized. Using a regular perturbation in the Deborah number, with the con ventional lubrication solution as the leading term, a solution can be obtained. Viscoelasticity may raise or lower pressure depending on the nature of edge boundary conditions.