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University of Wisconsin - Madison College of Engineering
Photo of Rolf Reitz.

Rolf D. Reitz
Mechanical Engineering

With pioneering contributions that span both experimental and computational studies, Rolf Reitz is a world leader in modeling liquid sprays. As a result of his contributions, researchers in academia and industry have made significant advances in internal combustion engine design and performance.

In research of fuel-injected engines, the complexity of fuel-spray behavior and the sheer number of variables—fuel-injection speed, drop size, air flow, drop velocity, and others—restricts researchers’ ability to fully understand the physics of the process. Yet, this very understanding plays an important role in increasing engine efficiency and decreasing emissions. At UW-Madison, Reitz and colleagues focus heavily on diesel engines through the Engine Research Center.

Informed by his experimental research, Reitz has developed computer models that have enabled researchers worldwide to more reliably predict spray behavior. His 1982 paper, “Mechanism of atomization of liquid jets” (authored with Princeton University Mechanical Engineering Professor Frediano Bracco), established a mathematical framework for capturing the physics of liquid spray atomization. It remains the standard reference used to describe diesel spray atomization.

Five years later, Reitz and Ramachandra Diwakar of General Motors Research Laboratories authored the paper, “Structure of high-pressure fuel sprays,” which introduced the element of drop breakup and significantly improved the reliability and accuracy of spray modeling. However, near-nozzle conditions affect diesel spray modeling and Reitz’s 1998 paper, “Modeling the effects of fuel spray characteristics on diesel engine combustion and emissions,” with then-graduate student Mark Patterson, provides extensive refinements to his earlier computational fluid dynamics model. This latest model was key to useful and accurate results.

Aided by his models, Reitz has pioneered the use of computational fluid dynamics to understand basic physical processes and practical methods for reducing emissions and improving fuel economy. “Professor Reitz’s spray modeling approach has quickly gained a worldwide acceptance as a robust modeling approach for atomization and sprays,” says a colleague. “A testimony of the quality of his work is demonstrated by the fact that all commercial computational fluid dynamics software, as well as all open-source computational fluid dynamics software used for modeling two-phase, chemically reactive flows have incorporated Professor Reitz’s spray modeling approach.”