Effect of Weissenberg number on turbulent heat transfer and friction factor of viscoelastic fluids

The effect of the elasticity of viscoelastic fluids on heat transfer and drag reduction behavior was investigated with aqueous polyacrylamide solutions flowing turbulently in circular pipes. A new dimensionless number called the Weissenberg number was used to account for the elasticity of the fluid. It was found that the fully established friction factor and dimensionless heat transfer coefficient, decrease with increasing Weissenberg number for a fixed Reynolds number up to certain critical Weissenberg numbers for friction and for heat transfer which are 5 to 10 and 200 to 250 respectively. The Powell-Eyring model was used to calculate the characteristic time of each test fluid for determining the Weissenberg number. The influence of polymer concentration, fluid degradation, pipe diameter and solvent chemistry on the behavior of friction and heat transfer of viscoelastic fluids was found to be adequately accounted for in the Weissenberg and Reynolds numbers.