Secondary flow of non-Newtonian fluids - 2. Frictional losses in laminar flow of purely viscous and viscoelastic fluids through coiled tubes

Abstract

Measurements of frictional resistance for the laminar flow of purely viscous and viscoelastic liquids in curved tubes were made. The purely viscous fluid flow data showed excellent agreement with the theoretical predictions of the work of R. A. Mashelkar and D. V. Devarajan in the modified Dean number range of 70 to 400. Viscoelastic fluid flow data showed an interesting drag reduction effect even under laminar conditions. These data were correlated in terms of a Weissenberg number. The possible reasons for this effect were examined in the light of the low Dean number data of this work and the related evidence in the literature. The correlations for frictional loss estimation of purely viscous and viscoelastic fluids in curved tubes have been established for use in engineering design.