Mixing in stirred vessels is an everyday routine process in almost all food, consumer goods, and pharmaceutical industries. The aim of this project was to predict the flow behaviour using high-fidelity computational simulations within mixing processes in stirred vessels containing miscible liquids with high viscosity ratios. The computational framework developed by our team makes use of accurate multi-phase flow models to predict the mixing time, which is a critical design parameter or assessing the mixing efficiency and is applied to compare the performance of different mixing vessels in industry. An experimental set up was also developed as part of this project using electrical resistivity tomography (ERT) technique, providing invaluable data for validating the CFD simulations.