Study On Particles Settling And Migration And The Drag Model In VES Wormlike Micellar Fluids

Particle settling and migration behavior is widely present in nature and industrial production processes,and the behavior of particle motion in different fluids varies greatly.VES wormlike micellar solutions are often used in the petroleum industry for sand transport in fracturing fluids,and the two-phase flow dynamics of particles in VES wormlike micellar solutions is both a prerequisite for the accurate description of multiphase flow of particles in these complex fluids and a key to solving engineering problems involving the multiphase flow in relevant industry.In this article,experimental and numerical simulations are used to measure the rheological properties of VES wormlike micellar fluids,and numerical simulations of rheological properties are performed using different types of non-Newtonian fluids to obtain the relationship between the constitutive equations and their rheological properties.The shear rheological curves are close to exponential curves.The experimental results were used to fit the curves of the constitutive equations,and it is found that the Giesekus model,which takes into account the shear thinning effect,and the Herschel-Bulkley model,which can describe the shear rheological properties of viscous solutions,are more suitable for VES wormlike micellar fluids.The effect of fluid rheological parameters(Deborah number De,characteristic viscosity ratio ζ,and mobility factor α)on particle settling kinetics was analyzed in a three-dimensional direct numerical simulation of a single particle settling in a VES wormlike micellar fluid,and the mechanism of the instability of particle’s settling velocity in VES wormlike micellar fluids was revealed.The combined effect of the elasticity and the negative wake is the ultimate cause of the instability of particle settling velocity.The Giesekus viscoelastic constitutive model considering the shear thinning effect was used to study the influence of rheological parameters on the drag of spherical particles,and a mathematical model based on the artificial neural network was proposed for the drag predications of particles in VES wormlike micellar solution and other shear thinning viscoelastic fluids.The spherical particle drag force can be predicted for given rheological parameters using this model.An experimental device which can be used to transport sands in complex fracture is built.The dilute particles setting and migration in pure water and VES wormlike micellar solutions are investigated.By comparing with pure water,we found that the particle transport performance of VES wormlike micellar fluid at small concentration is much larger than that of the pure water,but as the particle concentration increases,the particle deposition will be similar to that of pure water.However,the sand transport performance is still better than that of pure water.The Herschel-Bulkley constitutive equation,which is less expensive to compute,is used in the numerical calculations,and the simulation results indicate that the sand particles are well suspended in the fracture,which is basically consistent with the experimental observations.