Non-Homogeneus Boundary Conditions and Cavitation Modeling for Reynolds Equation

Abstract

When simulating numerically the hydrodynamical lubrication of tribological devices, a common assumption is that the boundary pressure and the cavitation pressure are equal (and taken equal to zero). This allows to include cavitation effects through some of the available algorithms, like the mass-conserving Elrod-Adams cavitation model. However, tribological devices often work under nonhomogeneous pressure conditions. An example of this is the cylinder/piston-rings system, where the pressure difference between both sides of the ring reach levels in the order of 50 atm during compression and ignition. In this work we propose an extension of the Elrod-Adams model in order to accommodate such non-homogeneous pressure conditions by assuming a dependence of the algorithmic cavitation pressure on the saturation variable. A first algorithm for solving the resulting model is proposed. Also, preliminary tests results on how the back-pressure may affect the dynamics of the rings during the compression/power stroke are reported.