Analysis of Lubricant Flow Through Reynolds Equation

K.C. Koppenhoefer[1], S.Y. Yushanov[1], L.T. Gritter[1], J.S. Crompton[1], and R.O. Edwards[2]
[1]AltaSim Technologies LLC, Columbus, OH, USA
[2]Cummins Fuel Systems, Columbus, IN, USA

Reynolds equation is used to analyze fluid flow through small gaps. As such, the solution of Reynolds equation provides critical information for a wide range of tribological problems. In any case where a lubricant resides between two moving surfaces, the Reynolds equation can be used to solve for the flow. In the case considered in this paper, lubricant flows between a piston and housing forced by a pressure differential along the lubrication path. As this pressure decreases, the lubricant heats and this heat is conducted through the piston and housing. The length scale difference between the lubricant thickness and the piston diameter represents a significant challenge to multiphysics software packages that do not have the ability to include weak form boundary conditions. In COMSOL Multiphysics v3.5a, Reynolds equation could only be fully implemented as a weak form boundary condition. In COMSOL Multiphysics v4.0a, the Reynolds equation has been implemented in the CFD module. This paper compares the weak form solution developed in Version 3.5a with a solution of this same problem using Version 4.0a.