An efficient computational model for simulating flow in stirred vessels: a case of Rushton turbine

Abstract

Computational tools are being increasingly used to analyse flow and mixing in baffled stirred vessels. In a baffled stirred vessel, flow around the rotating impeller blades interacts with stationary baffles and generates a complex, three-dimensional, recirculating turbulent flow. We have developed an efficient computational model, in which a quasi-steady flow is computed for any momentary impeller position. This model adequately captures most of the significant details of the flow both within and outside the impeller without requiring any empirical input/ adjustable parameter. The method was applied to the flow generated by a standard Rushton turbine, for which detailed experimental data are available. A case of fully baffled vessel with standard Rushton turbine (DT) was simulated using FLUENT code. The impeller rotation was modelled in terms of appropriate source terms at the blade surfaces. The laminar and turbulent flow generated by DT were simulated using this model. The model predictions were validated by comparisons with the published experimental data. Overall impleller performance characteristics like pumping number and power number were also compared with the experimental data for both, laminar and turbulent flow regimes. The approach presented here can be used as a general purpose, mixer design tool.