Simulations of a sphere sedimenting in a viscoelastic fluid with cross shear flow

Simulations of a sphere sedimenting in a viscoelastic fluid with cross shear flow

► Increasing shear Weissenberg number increases the drag (reduces settling rate). ► The simulation results are in qualitative agreement with the experiments. ► The increase in drag is primarily due to the τ11 component of the viscous stresses. ► Non-linear coupling due to the polymers increases the...

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Bibliographic Details
Published in:Journal of non-Newtonian fluid mechanics 2013-07, Vol.197, p.48-60
Main Authors: Padhy, S., Shaqfeh, E.S.G., Iaccarino, G., Morris, J.F., Tonmukayakul, N.
Format: Article
Language:eng
Subjects:
Computational fluid dynamics
Computer simulation
Drag
Fluid flow
Fluids
Mathematical models
Particle sedimentation
Settling
Settling rate
Shear flow
Suspension
Viscoelasticity
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Summary:► Increasing shear Weissenberg number increases the drag (reduces settling rate). ► The simulation results are in qualitative agreement with the experiments. ► The increase in drag is primarily due to the τ11 component of the viscous stresses. ► Non-linear coupling due to the polymers increases the viscous stresses. ► The mechanism is the break in symmetry of the shear flow by the uniform flow. The settling rate of heavy spheres in a shear flow of viscoelastic fluid is studied by numerical simulation. Experimental data [Tonmukayakul et al., US Patent Application US20110219856 (2011); van den Brule and Gheissary, J. Non-Newton. Fluid Mech. 49 (1993) 123–132] have shown that both shear thinning and the elasticity of the suspending polymeric solutions affect the settling rate of the solids. In the present work, simulations of viscoelastic flow past a single, torque-free sphere with a cross shear flow are used to study the effect of the elasticity of the carrying fluid on the sphere’s settling rate. The FENE-P constitutive model is used to represent a viscoelastic Boger fluid, with parameters obtained by fitting rheological data. A twofold increase in drag, i.e. a decrease in settling rate, is obtained with increase in the cross shear Weissenberg number, Wi⩽15, even though the shear viscosity of the solution decreases over this same range. At small Weissenberg number, Wi
ISSN:0377-0257
1873-2631