(564a) North American Mixing Forum Award Lecture: The Progression of Computational Fluid Dynamics As a Tool for Process and Equipment Design in Mixing

In industrial equipment design, tools used are often a balance of cost and accuracy. This is true of both experimental and computational tools. Computational Fluid Dynamics (CFD) has been a tool used by the mixing industry since the early 1990s in various forms. Early practical applications in rotating mixing used extensive symmetry assumptions and experimental impeller discharge boundary conditions to allow for practicable insights to be gained. These tools were an excellent example of George E. P. Box’s adage, “All models are wrong, but some are useful.” The simulations were not “right,” but they were useful, allowed for quick optimization, and were an excellent supplement to experimental work.

As computers became more powerful and simulation codes became more sophisticated, so did the ability to use CFD as a tool. By the mid-2000s, 3D simulations using CAD geometries were commonplace for more complicated applications. For large, complex projects, they offered insights that were difficult, expensive, or nearly impossible to extract experimentally.

While large eddy simulations (LES) and Lattice Boltzmann method (LBM) techniques were used for many years in academic and nation-state scale applications, by 2015, they had become tractable for industrial-scale applications. This allowed time-accurate physics to be simulated at scales and flows that could mimic industrial-scale applications. Phenomena such as time-accurate transient forces on mechanical components (fluid-structure interactions), reactions, and surface processes could be simulated in a time frame that would be immediately useful.

Looking ahead, a continued combination of lower cost and faster computational capabilities, along with fast-growing technologies like machine learning, will accelerate the use of CFD as a primary design and troubleshooting tool. Ultimately this will allow for industrially tractable, fully turbulent, transient simulations, including wall-controlled phenomena (e.g., heat transfer), to be completed and even coupled with mechanical analyses. As these tools develop further, more and more of the applications of CFD will be performed by practitioners rather than modeling experts.

This talk will look back at several snapshots in time to review the impact of the simulation tools of the time, reflect on the current state of the art and look forward to some of the next significant impacts of CFD. It will also examine mixing tasks where CFD can be used as a tool to easily, accurately, and effectively capture needed engineering answers and examine tasks that currently require users to be modeling and mixing experts.