Stirred mixing vessels are widely used in chemical industry for processes involving the mixing or/and chemical reactions of liquids

gases or solids.The ability to numerically simulate the whole flow field is vital to optimal design.Previous attempts have adopted a steady-state semi-empirical analysis requiring experimentally-based inputs of some form.In the present work

the CFD code CFX-4 is used for the full field computation for both the fluid within the impeller passages and the fluid outside.The model solves the unsteady ensemble-averaged continuity and momentum equations(Reynolds equations)with turbulence effects accounted for by k-ε model

RNG k-ε model

and algebraic stress model.The equations are discretised by the finite-volume approach.The mesh is divided into two parts which are fixed to their respective frames of reference

one being stationary and the other rotating with the impeller. At the interface between these two parts the rotating mesh slides over the fixed one at each time interval.The computation proceeds simultaneously over the whole flow field and the solutions in both rotating and stationery domains are coupled at all times.Comparisons between the predictions and the experimental data measured by particle imaging velocimetry(PIV)show that all the major flow patterns are well reproduced. The quantitative comparisons show encouraging agreement.