On the use of non-planar geometry to improve squeeze film rheometry

Abstract

This paper presents an investigation into the effects of plate misalignment in oscillatory squeeze film analysis. In order to achieve an exact solution to the lubrication approximation including misalignment, the problem is considered in two dimensions where it is noted that plate force increases with plate skew angle. This behaviour is seen in experimental tests with a spherical plate but not for the case of flat plates. For flat plates, the force drops at low film heights and large tilt angles, which is understood to occur due to the position of the centre of pressure in the film. For the flat plates, the centre of pressure moves towards the edge of the plates, and in the three-dimensional situation this will create a shorter leak path thereby reducing the pressure in the film. From the understanding of the phenomena displayed, a conical geometry is proposed and tested which shows superior performance to the spherical surface when estimating the viscosity of a Newtonian fluid.