Non-newtonian rheology on curved circular squeeze films using the Rabinowitsch fluid model

Squeeze film lubrication plays a crucial role in many mechanical systems such as gear mechanisms, thrust bearings, artificial joints, and clutch plates. Classical lubrication studies often assume Newtonian fluids; however, modern lubricants frequently exhibit non-Newtonian rheological behavior due to polymer additives and complex molecular structures. In the present study, the squeeze film behavior between curved circular plates is analyzed using the Rabinowitsch non-Newtonian fluid model. The governing Reynolds-type equation for the non-Newtonian lubricant is derived from the momentum and continuity equations under the assumptions of thin-film lubrication theory. A perturbation approach is employed to obtain an approximate analytical solution for the pressure distribution within the lubricant film. The effects of the nonlinear rheological parameter and the curved shape parameter on the pressure profile, load-bearing capacity, and squeezing time are examined. Numerical computations demonstrate that dilatant lubricants significantly enhance load capacity and extend the squeezing response time compared with Newtonian fluids. In contrast, pseudo-plastic fluids tend to reduce load support but allow faster surface approach. The results also reveal that concave geometries improve lubrication performance more effectively than convex geometries. These findings provide valuable insights into the design of advanced lubrication systems utilizing non-Newtonian fluids in curved mechanical interfaces.

Keywords: Non-Newtonian Lubrication, Rabinowitsch Fluid Model, Curved Circular Plates, Reynolds Equation, Squeeze Film Lubrication, Load Capacity, Pressure Distribution.