Newtonian viscosity measured by impression test

The problem of viscous flow beneath a flat-end planar as well as a cylindrical punch was analyzed when the punch was pressed onto the surface of a semi-infinite Newtonian fluid by a small load. The steady state penetration velocity of the punch was found directly proportional to both the punching stress and the size of the punch and inversely proportional to the viscosity. The relation among these parameters was not affected by the slip or stick boundary condition at the punch/liquid interface. So this ‘impression test’ should be a good way of measuring viscosity.