Viscoelastic fluids through porous media: flow instability and particle transport
Viscoelastic fluid flows through porous media are common in industrial and biological applications ranging from oil recovery and groundwater remediation to drug transport in tissue. Polymeric stresses affect the topology and stability of these flows, and thus, their macroscopic transport properties. We numerically study the flow topology, instability, and dispersion of viscoelastic flow through porous media. Inertial stresses here are negligible, and instead, the flow is dominated by elasticity and viscosity; their relative effects are characterized by the Weissenberg number. At small Weissenberg numbers, stable eddies appear, whereas at large Weissenberg numbers, strong flow fluctuations due to high polymeric stresses lead to the formation of highly unstable eddies in different regions of the pores and multiple distinct unstable flow structures occur. The stretched polymeric chains inside the pore facilitate eddy formation, whereas relaxed chains lead to eddy free regions. We also discuss the dispersion of particles in these flows.