Abstract
Theoretical basis for a newly developed damped oscillation rheometer is presented for a Newtonian fluid. This rheometer essentially consists of a cylindrical tube suspended by a torsion wire and filled with fluid to be tested. The damped oscillation of the cylinder is observed. Based on some assumptions, the equations of motion for a Newtonian fluid in the tube are solved. The numerical solution and some approximate solutions valid for certain ranges of parameters are obtained. From these solutions the logarithmic damping factor and the period of oscillation are obtained as functions of fluid viscosity.
