This report addresses the properties of flow in a funnel or hopper. One aspect of this work is to better understand and interpret results using the Flowdex tester. This device is used to characterize flowability, and in particular to characterize that property for various powders of interest to P&G. This work has benefitted from collaborative interactions with Paul Mort of P&G.
The Flowdex tester consists of a cylinder with a small hole at the bottom. Thematerial to be tested resides in this cylinder. The typical dimensions are a a half dozen centimeters for the cylinder diameter, and about 10 cm for its height. A release mechanism provides a rapid opening mechanism for the plug at the bottom of the cylinder.