Measurement of Friction Coefficient on a Powder Layer and Fluid Dynamic Study

The friction coefficient was measured for about 80 runs under different conditions. A table of the conditions and results is shown in Appendix-5. The major conditions are:

• The surface of the track board is plywood.
• Pressed flour is used as powder material.
• Powder is adhered to the lower surface of the disk

The sliding situation under this conditions was recorded and edited into Movie 2 and the results are described in this section. Other results are discussed  in the section of the comparison experiment.

The track in the powder layer The time rate of change of disk velocity The friction coefficient The critical speed at which the friction coefficient change Visualization of shear motion in the powder layer The sliding position of a disk

Movie 2.  The sliding of disk on the flour layer. This movie was edited to contain the view of sliding disk  from above, the view  from end of the sliding , and the track left in the powder layer.

Measurement of Friction Coefficient on a Powder Layer and Fluid Dynamic Study