Flow characteristics associated with abrupt changes in geometry in the case of highly elastic liquids

Abstract

Consideration is given to the influence of small changes in corner geometry on flow characteristics in the case of elastic liquids flowing in various contraction geometries. Both Boger fluids and aqueous solutions of polyacrylamide are used to show that it is very difficult to make generalizations from one geometry to another or from one type of non-Newtonian fluid to another. Of major importance is the observation that the precise mechanism of vortex enhancement varies with the contraction ratio. For large contraction ratios, a re-entrant corner vortex (not present in a 4:1 contraction) is shown to have an important influence on the development of vortex enhancement. © 1986.