Liquids in Motion: An Investigation into Newtons Model for Viscosity

Abstract

Colin John Cook

Newton’s model of viscosity in liquids employs a fixed plate and a parallel moving plate separated by a gap. The moving plate takes a conceptual liquid layer along with it and the stationary plate holds a similar liquid layer in place. This creates shear between the layers, and the differences in speeds between layers was assumed to be an arithmetic pro- gression to zero. Experimental results and logic indicate: no zero velocity in such a system, relative speeds are actually in geometric progression, and that therefore Newton’s model is incorrect.

Dimensional analyses of a rotating cylinder and a moving plate in viscous liquids both give the dimensions of viscosity as M/(L2 .T), whereas the currently accepted unit of viscosity, the poise, has dimensions M/(L.T). Therefore, the poise has been incorrectly assigned to viscosity, and existing formulas lack predictive power.

PDF