On the flow of Newtonian and non-Newtonian liquids through corrugated pipes

Abstract

Consideration is given to the flow of Newtonian and non-Newtonian liquids through a “corrugated” pipe of circular cross section whose radius sinusoidally along its longitudinal axis. The flow is produced by a constant pressure gradient. The theory predicts that in the Newtonian case, the corrugated wall of the pipe causes a reduction in flow rate when compared with the value expected on the basis of a straight pipe of the same mean radius. This prediction is confirmed by experiment. In the case of elastico-viscous liquids, the theoretical analysis for a certain fluid model indicates that the reduction in flow rate may be amplified or reduced by the non-Newtonian properties of the liquid depending on the precise flow conditions. The qualitative predictions are again confirmed by experiment. The possible practical implications of the work are outlined.