I'm working on a project at work that requires some tribology/fluids calculations that I don't know if are applicable to me or not. For this scenario, one of the tests will require me to assume hydrodynamic lubrication where oil is completely separating the 2 surfaces. I have a sliding steel plate being inserted into the opening of a hollow, steel tube. The plate is being pressed against the tube wall simultaneously as it enters the tube. The steel tube is coated with an oil but of unknown film thickness and distribution (I can assume even distribution and am guessing have to assume a thickness). The steel plate is shaped to the curvature of the tube and will be held against the tube wall by an applied force which I can control. I want to find out the axial force that is required to overcome friction and pull the plate out of the tube. I have been given the kinetic viscosity of the oil and am looking for the density to calculate dynamic viscosity. Once I have the dynamic viscosity, I know I can calculate viscosity shear force using the Newton equation of: force = dynamic viscosity x area x (dx/dy). The problem is, I don't know the velocity gradient dx/dy because the oil is initially stationary and I don't know how it will move when the plate comes into contact with the tube wall. I also don't know the thickness of the oil film at any time. For the purpose of this test, I am assuming that the majority of the oil is not getting displaced enough to cause surface to surface direct contact (i.e. boundary lubrication). I am not a tribologist and am a pretty poor ME so any help would be appreciated! Thanks very much!