CFD simulation of free liquid surface motion in a pilot plant stirred tank

Abstract

The Volume of Fluid method together with the Large Eddy Simulation technique for turbulence flow was used for CFD prediction of liquid flow and free liquid surface motion in a pilot plant cylindrical flat-bottomed stirred tank with an inner diameter of 1 m filled with tap water at room temperature. A pitched-blade (45 • ) down pumping impeller (diameter of 0.33 m) with six blades was used for stirring. The impeller speed was 180 rpm. For simulation of the impeller motion, the sliding mesh method was adopted. The CFD simulations of the flow field predicted a highly complex, multi-dimensional dynamic system exhibiting unstable, pseudo-stationary behaviour. The main advantage of this CFD simulation is the prediction of the velocity flow patterns and the free surface elevation/depression in the whole system at one time. The results for the location and dimensions of the free liquid surface fluctuation correspond well with an experimental investigation by a conductivity method.La méthode de volume de fluide avec la technique Large Eddy Simulation pour le flux de turbulence aété utilisée pour prédire la DFN du flux de liquide et du mouvement de la surface liquide libre dans la cuveà agitation cylindriqueà fond plat d'une usine pilote avec un diamètre interne de 1 m remplie d'eau du robinetà température ambiante. Un impulseurà pompage descendantà pales inclinées (45 • ) (diamètre of 0,33 m) avec six pales aété utilisé pour l'agitation. La vitesse de l'impulseurétait de 180 tr/min. Pour la simulation du mouvement de l'impulseur, la méthode des maillages glissants aété adoptée. Les simulations de la DFN du champ du flux ont prédit un système dynamique multidimensionnel très complexe qui affiche un comportement pseudo-immobile et instable. Le principal avantage de cette simulation de la DFN est la prédiction des modèles de la vitesse d'écoulement et l'élévation ou la dépression de la surface libre dans tout le système en même temps. Les résultats de l'emplacement et des dimensions de la fluctuation de la surface liquide libre correspondent bienà l'analyse expérimentale par une méthode de conductivité.

Free‐Surface Turbulent Flow in an Eccentric Stirred Tank

“…The evolution of vortex height during its growth was successfully captured. VOF together with LES was used for prediction of free liquid surface motion in a stirred tank by Jahoda et al [25]. The predictions were found to be in good agreement with the experimental results.…”

“…The wall adhesion force was also considered by specifying the contact angle q w aŝ n ¼n w cosq w þt w sinq w (25) wheren w andt w are the unit vectors normal and tangential to the wall, respectively.…”

Free Surface Turbulent Flow in an Unbaffled Stirred Tank: Detached Eddy Simulation and VOF Study

“…They did not give the reason, and we think this may be due to the weakness of the RSM model they had used. In a recent study, VOF together with the LES model was used for prediction of liquid flow and free liquid surface motion in a stirred tank by Jahoda et al (2011). 5 The predicted results were found to be in good agreement with an experimental investigation by a conductivity method.…”

“…In a recent study, VOF together with the LES model was used for prediction of liquid flow and free liquid surface motion in a stirred tank by Jahoda et al (2011). 5 The predicted results were found to be in good agreement with an experimental investigation by a conductivity method. The VOF model was also used by Motamedvaziri and Armenante (2012) 15 to model the air-water interface in stirred vessels for different liquid fill ratios.…”

“…[1][2][3][4] But in fact, the liquid surfaces in baffled stirred tanks are wavy. There is surface macro-swell, i.e., elevation/depression of the liquid surface with time (Jahoda et al, 2011).…”