Mixing vessels are widely used in the chemical industry to optimize mixing and/or heat transfer between fluids. Mixing must be efficient, precise and repeatable to ensure optimum product quality. Quantities of interest may include mixing times, gas hold-up, power draw, local shear and strain rates, and solids distribution. The application of Computational Fluid Dynamics to address these needs results in faster and lower cost design through reduced experimentation, more reliable scale-up, and better understanding of the processes, leading to higher yields and reduced waste.