This paper reports experimental study of the static and dynamic coefficient of friction, μs and μd, using 1-in. transparent or translucent pipes of four different materials; glass, acrylic resin, vinyl chloride, and polyvinylidene fluoride. Four different sizes of sand from 0.86mm to 2.18mm and sliding velocities from 1cm/s to 12cm/s were investigated. To determine these coefficients of friction, original apparatus were built.
Friction tests were administered to measure angles of an inclined plane on which solid particles start sliding for As and to measure friction forces of the particles pulling along at constant speeds for pd. The results of these are compared with the coefficients of sliding friction between a submerged sliding bed of solids and a pipe wall for saltation flow in a test pipeline constructed of the same materials as those for the friction tests of μs and μd.
The variation of the coefficient f with transport conditions are also discussed.
