Numerical simulation of solid suspension via mechanical agitation: effect of the modelling approach, turbulence model and hindered settling drag law

Abstract

This study uses the commercial CFD code ANSYS CFX to explore two different modelling approaches, EulerianEulerian (E-E) and algebraic slip modelling (ASM), for the simulation of the suspension of moderately concentrated slurries (10% by volume of solids). It is shown that the ASM provides a computationally efficient model that performs very similarly to the E-E model. The influence of the choice of turbulence model (phasic or homogeneous) and the role of turbulent dispersion forces are also investigated. In addition, the importance of interfacial drag modelling and other non-drag forces are examined. During this study, the existence of inherent hindered settling in the momentum equation formulation is noted and it is shown how it can be accounted for in hindered drag law implementation.

CFD Modeling of Solid Suspension in a Stirred Tank: Effect of Drag Models and Turbulent Dispersion on Cloud Height

“…Turbulence plays an important role in developing single-phase flow structures, and it is generally accepted that it will also have some influence on the solids distribution in stirred tanks. Previous CFD investigations have highlighted the importance of turbulence-assisted solids dispersion in stirred tanks [16][17][18][19][20]. However, a quantitative evaluation of the effect of turbulent dispersion on cloud height has not been considered in detail.…”

CFD simulation of solid–liquid stirred tanks for low to dense solid loading systems

“…that were neglected in the study. Ochieng and Lewis (2006b), Fradette et al (2007), Ochieng and Onyango (2008), Kasat et al (2008), Fletcher and Brown (2009), Tamburini, Cipollina, Micale, Ciofalo, and Brucato (2009), Tamburini, Cipollina, Micale, Brucato, and Ciofalo (2011) and Tamburini et al (2012) conducted simulations for volume fractions below 20 %, and validated using non-local properties like cloud height, suspension quality, etc. In another similar study, Gohel, Joshi, Azhar, Horner, and Padron (2012) used qualitative and quantitative data for cloud height to validate the simulation of high concentration solids suspension in stirred tanks.…”

“…Computational Fluid Dynamics (CFD) modelling has been used successfully to understand the hydrodynamics of multiphase stirred tanks, especially at lower solids concentration (Fletcher & Brown, 2009;Kasat et al, 2008;Tamburini, Cipollina, Micale, Brucato, & Ciofalo, 2012, 2014. However, multiphase CFD models rely on a variety of constitutive models that needs validation, which was otherwise not possible due to unavailability of reliable data at high solid concentration.…”

CFD Modelling of Flow and Solids Distribution in Carbon-in-Leach Tanks

“…that were neglected in the study. Ochieng and Lewis [6], Fradette, et al [7], Ochieng and Onyango [8], Kasat, et al [9], Fletcher and Brown [10], Tamburini, et al [11][12][13], conducted simulations for volume fractions below 20%, and validated using non-local properties like cloud height, suspension quality, etc. In another similar study, Gohel, et al [14] used qualitative and quantitative data for cloud height to validate the simulation of high concentration solids suspension in stirred tanks.…”