On the flow of viscous and elastico-viscous liquids through straight and curved pipes

Abstract

An experimental study is described which seeks to assess the effect of elasticity on the flow of elastico-viscous liquids as they are made to flow through curved pipes under a pressure gradient. Wherever possible, the experimental results are discussed in the light of existing theoretical predictions and good agreement between theory and experiment for viscous and elastico-viscous liquids is indicated. The general flow pattern for elastico-viscous liquids is shown to be similar to that for Newtonian liquids consisting of two spirals separated by the central plane. Elasticity has a significant effect on the pitch of these spirals. The flow rate in the case of laminar flow and in the transition region between laminar and turbulent flow is significantly enhanced by the presence of elasticity in the liquids, but the opposite is the case in turbulent flow at high Reynolds numbers.