Our ultimate goal is to model mixing so that computational approaches can make experimental measurements unnecessary. Our view must be well based in fundamentals, but at the same time be clearly directed to solving real world engineering problems. Mixing is a major issue in the process industries. To contribute to the solution of this problem, our attention is focused on two systems. The first, simplistic, but still of industrial importance, is the opposed jet mixer. The second, much more complex and of major industrial importance, is the 'standard' impeller mixing vessel. The first system is key to the validation of computational results. The second system is key to mixing, effective chemical reactions and the reduction of by products in complex reactions that can be detrimental to the environment.