CFD determination of macro-scale concentration distribution in stirred tank

Batch mixing of a tracer in a stirred tank was simulated by means of a comm ercial CFD code and the probability distribution of the tracer concentratio n was studied. Two mixer configurations along with three modes of tracer ad dition were examined. It is found that the effect of the mixer configuratio n on the values of the probability density function is manifested virtually throughout the entire process, whereas that of the addition mode gradually diminishes as the process progresses. The effect of the scale of scrutiny on the concentration distribution was analysed using five scale levels and its importance is confirmed in the initial period of homogenisation. The ap plicability of the beta function to model the probability density function obtained numerically was evaluated. It is concluded that the beta model doe s not fully reflect the distribution complexity.