CFD Modelling of Elastohydrodynamic Lubrication

Abstract

Traditionally the problem of elastohydrodynamic lubrication (EHL) has been solved using the Reynolds equations for fluid flow. In this paper we explore the finite volume method (FVM) to model fluid behaviour in rolling-element bearing systems. The effect of cavitation is modelled with a barotropic cavitation model. We investigate two cases with a cylinder on a flat plate, one under rolling and one under sliding conditions. These solutions are compared to the Reynolds-EHL approach. Towards higher loads, stability problems are encountered and strategies for dealing with these are discussed.

A Computational Fluid Dynamics Study on Shearing Mechanisms in Thermal Elastohydrodynamic Line Contacts

“…For modeling non-Newtonian fluid behavior two rheological models are used, the Ree-Eyring and the Carreau. The Ree-Eyring model reads [24] η Ree−Eyring p, T,…”

“…Surface temperature, evaluated at location x and caused by heat flux q f acting at locationx, was computed according to Carslaw-Jaeger thermal boundary condition that for 1D line contact reads [24]…”

“…where index s denotes the solid part. However, Equation (35) has the limit of applicability depending on the Peclet number that can be calculated by using formula [24]…”

“…For EHL contacts, the characteristic length scale is the Hertzian half width b. Finally, in order to use Equation (35), it is recommended that the Peclet number is larger than 5 [24]. In 2018, Hartinger [25] showed that for the EHL line contact problem, surface temperatures predicted by Carslaw-Jaeger equation closely matched experimental measurements.…”

A General Finite Volume Method for the Solution of the Reynolds Lubrication Equation with a Mass-Conserving Cavitation Model

“…Additionally, the double parabolic slider case also proposed by [33] is used to assess the capability of the EbFVM for predicting the fluid-film reformation boundary. The results are compared both with respect to a CFD analysis based on the full solution of the Navier-Stokes equations developed using the Open-FOAM code [34], as well as with the same methods employed by Sahlin et al [33] and Bertocchi et al [14]. The consideration of CFD solutions as a comparative basis is aimed to (1) ensure the validity of Reynolds equation for flow problems which satisfy the fundamental lubrication hypotheses, and further (2) demonstrate that in common lubrication applications the intricate flow behavior of the liquid-vapor/gases mixture within the cavitation zones is in general meaningless for the overall predictions of the system performance.…”