Factored-lmplicit Finite Difference Solution of a Non-Newtonian Fluid Lubrication Equation for Three-Dimensional Bearings

A time dependent lubrication equation is developed for a non-Newtonian fluid whose shear stress is expressed in terms of instantaneous strain rate. By expanding the shear stress through a two function Taylor series, the stress/strain-rate relationship is linearized within the time interval (tⁿ ≤ t ≤ tⁿ⁺¹) but accurate to O(Δt²). This produces a linear lubrication equation which is second-order time-accurate. The resulting finite difference form of the lubrication equation is then factored and split into two equations, each of which represents a sequence of one-dimensional systems of tri-diagonal scalar equations. A finite difference code based on this algorithm was written called VISQUSFLO which provides static and dynamic analysis of the head/disk interface of data storage systems. Numerical examples of a shear-thinning fluid are presented for clearances in the range of 25-50 nm for finite width slider bearings.