An Eulerian-Eulerian Model for the Dispersion of a Suspension of Microscopic Particles Injected Into a Quiescent Liquid

Abstract

ABSTRACT:The convective dispersion of a suspension of microscopic particles injected into an initially quiescent liquid is examined using a finite volume, Eulerian-Eulerian computational fluid dynamics model. The motion of the phases is coupled with particle-particle interactions represented using a solids pressure formulation. The solids are of greater density than the liquid and settle after injection, creating a liquid flow field that eventually results in a toroidal plume of solids descending through the liquid phase. Excellent qualitative agreement between predicted plume shapes and published experimental shapes are obtained for 50 μm particles. For particle diameters less than 50 μm, the solids plume exhibits a toroidal recirculation in the liquid and particle phases relative to the downward motion of the plume. However, for particle diameters greater than 375 μm, a toroidal liquid recirculation is not predicted within the solids plume. The initial shape of the plume immediately after injection is affected by all parameters: density ratio, liquid viscosity, particle diameter, and injection parameters. It is concluded that it is this initial shape that determines the subsequent plume shape at a particular depth of penetration for varying solids density and liquid viscosity.

Influence of drag and turbulence modelling on CFD predictions of solid liquid suspensions in stirred vessels

“…This effect is especially relevant at intermediate impeller speeds: in fact, when the impeller speed is low, slip velocities are also low so that the dense particle correction does not provide appreciable effects, while at high impeller speeds the solids are more uniformly distributed and, again, drag corrections are of little consequence. Furthermore, for the case of the PwC approach, the drag force overestimation within the solid sediment region can further increase because of the adoption of Ergun's equation, despite its use at high local volume fractions is suggested by the literature (CFX-4 Documentation, 1994;Ochieng and Onyango, 2008;Holbeach and Davidson, 2009). In this regard, some cases can be found in the literature where the ad adoption of drag modification due to dense particle effects is found to provide unsatisfactory A c c e p t e d M a n u s c r i p t 44 predictions (e.g.…”

Turbulent flow of hydrates in a pipeline of complex configuration

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Eulerian-Eulerian CFD Model for the Sedimentation of Spherical Particles in Suspension with High Particle Concentrations

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