Abstract
Many important applications in the food industry, biological systems, and recovery of fluids from the subsurface involve multiphase flow dynamics where one of the phases is a non-Newtonian, viscoelastic fluid. In this work, we investigate the role of viscoelastic displacing fluids in recovering trapped nonwetting fluids. We perform the lattice Boltzmann (LB) modeling of wetting viscoelastic fluids described by a Maxwell model that displace nonwetting, trapped droplets in three different pore geometries. Results show the oscillation of the trapped nonwetting droplets and subsequent release induced by the viscoelasticity of the displacing fluid. The oscillation behaviors are in qualitative agreement with recent experiments in microfluidic chips and micromodels. The disorder of streamlines in viscoelastic fluids is reported in the presence of another phase, which explains the observation of oscillations. In the geometry of a capillary tube that converges to a smaller constriction/throat, a vortex downstream of the droplet is found to prevent the droplet from entering the throat. In the geometry of a tube with an “x-shaped” solid grain, we find that the oscillation strength and extraction capability of displacing fluids monotonically increases with their elasticity. The results from the geometry of a tube with a “dead-end” branch show a linear relationship between the average mean vorticity and the square root of the Deborah number before the release of droplets.
6 More- Received 16 August 2019
- Accepted 28 April 2020
DOI:https://doi.org/10.1103/PhysRevFluids.5.063301
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