Large eddy simulation of the gas–liquid flow in a stirred tank

Abstract

in Wiley InterScience (www.interscience.wiley.com).Both the large eddy simulation (LES) technique and the k-e turbulent model were used to simulate the gas-liquid turbulent flow in a stirred tank driven by a Rushton impeller. A Eulerian-Eulerian two-fluid model for gas-liquid two-phase flow was developed using the large eddy simulation for both gas and liquid phases. The relative movement of the rotating impeller to the static baffles was accounted for through the improved inner-outer iterative algorithm. The spatial discretization of the governing equations was performed on a cylindrical staggered grid. For the LES, a conventional Smagorinsky sub-grid model was adapted to modeling the turbulence of the liquid phase. The momentum and continuity equations were discretized using the finite difference method, with a third order QUICK (Quadratic Upwind Interpolation for Convective Kinematics) scheme used for convective terms. The phase-resolved predictions of the LES were compared with the experimental data and the simulation results by the standard k-e model, suggesting that the LES has much better accuracy than the k-e model.

Modeling of aerated stirred tanks with shear-thinning power law liquids

“…Montante et al (2007Montante et al ( , 2008) solved a population balance equation (PBE) with breakup and coalescence models to predict the local bubble size distribution (BSD). Zhang et al (2008) employed an inner-outer iterative algorithm to model the fluid motion induced by the impeller blades. They concluded that large eddy simulation (LES) provided a greater accuracy than the standard k-e model for the prediction of the mean liquid flow field and the gas holdup.…”

Quantifying sub-grid scale (SGS) turbulent dispersion force and its effect using one-equation SGS large eddy simulation (LES) model in a gas–liquid and a liquid–liquid system

“…The Eulerian-Eulerian large eddy simulation (LES) turbulence model has shown significant promise in unearthing flow details in multiphase systems like, in gas-liquid multiphase systems (Deen et al, 2001;Dhotre et al, 2008;Tabib et al, 2008;Zhang et al, 2008;Niceno et al, 2008), in liquid-solid particle systems involving stirred vessel (Derksen, 2006), in fluidized bed (Chiesa et al, 2005) and particle laden flow (Riber et al, 2009). Though there is one drawback while applying the Eulerian-Eulerian LES, that is in-order to maintain the consistency of the assumption of interpenetrating continua, the largest interface details should be smaller than the grid size, which means that the cell size must be larger than the particle size.…”

Enhanced Mass Transfer in Stirred Tanks

“…In addition, CFD may be used for the design and optimization of stirred tanks either for solid-liquid mixing (Fig. 8) or gas-liquid mixing [31,32].…”

“…This type is more appropriate for dispersion of gas in liquid [31,32]. In this case, LES are conducted to study the path and shape of single air bubbles rising freely in water.…”