Owing to computational efficiency and model simplicity, the engulfment model (E-model) is more suitable for studying micro-mixing in industrial scale reactors. However, the E-model does not contain the information of macro-mixing on the reactor scale. A CFD method coupled with the E-model is proposed and implemented to predict the micro-mixing in stirred tanks. The new modeling approach describes the small-scale segregation of fluid by solving the transport equations of mixture fraction and its variance based on the simulated macro-flow, and calculates the representative turbulence kinetic energy and dissipation in the reaction zone via the weighted average of mixture-fraction variance for the E-model. The predictions of segregation index compare with experimental results satisfactorily. (C) 2015 Elsevier Ltd. All rights reserved.