Creeping Flow of Viscoelastic Fluid through a Packed Bed

Experimental results on investigation of elastic effects in creeping flow of viscoelastic fluids through a packed bed of spherical particles are presented. A simple form of the corrective Weissenberg number (We) function is proposed to extend the use of the Ergun equation, applicable to fixed bed flow of purely viscous fluids, for the prediction of friction factor in creeping flow of viscoelastic fluids. In order to quantify the effect of fluid elasticity on frictional pressure drop, aqueous solutions of polyacrylamide in the concentration range of 0.25%-0.6% (wt/vol) were used as test fluids and an extensive pressure drop-flow rate data were generated. Friction factor or pressure drop exhibited asymptotic behavior with variation in We, depicting the onset of viscoelastic effects at critical We values with a magnitude of 0.1 and the dominance of elastic effects over inertial effects up to We = 1.1. The percentage drag enhancement, as a function of fluid relaxation time, in the applicable range of We, is also reported. The proposed correlation will be useful in the field of enhanced oil recovery.