Alva L. (Tad) Addy


For his distinguished research in fluid dynamics and outstanding leadership of an academic department that influenced thousands of mechanical engineers, as well as his advocacy for the quality and innovation in education.

Professor Emeritus, Department of Mechanical Science and Engineering at Illinois

  • BS, 1958, Mechanical Science and Engineering, South Dakota School of Mines and Technology
  • MS, 1960, Theoretical & Applied Mechanics, University of Cincinnati
  • PhD, 1963, Mechanical Science and Engineering, University of Illinois

Alva L. Addy, more affectionately known as Tad, is a pioneer of fluid mechanics. Addy graduated from Illinois in 1963 with a PhD in mechanical engineering. He attributes his time at Illinois as what motivated him to conduct research on ejectors and separated flows.

He began this research while attending Illinois as a graduate student in the Department of Mechanical Science and Engineering, formerly known as the Department of Mechanical and Industrial Engineering. After earning his PhD, he joined the faculty in the department and he continued researching innovative theoretical flow models. These models were the first departure from piecewise one-dimensional analysis to an integrated two-dimensional interaction model with viscous mixing. They established a foundation to the understanding of ejector theory and operation that has become a classic.

Addy also made lasting contributions to the areas of base drag and separated flow. He investigated specialized applications in missile and aircraft propulsion and fundamental contributions to the understanding of high-energy chemical laser performance. His research was so impressive that the US Army Research Office and the US Army Missile Command funded him and his colleagues continuously for more 30 years.

His research models provided powerful estimates of the behavior of phenomena in high-speed compressible flows that had not been previously understood. Addy used this information to build computer programs that were widely used by military and civilian aircraft and missile propulsion systems designers during the 1960-1980s.  Among the most notable projects his system was used for were the Concorde and the Space Shuttle.

In addition to being a successful researcher, he was also an award-winning faculty member at Illinois. His enthusiasm for teaching, support for interdisciplinary team projects, student societies, and general student concerns made him popular among undergraduates. Additionally, in 1993, a college-wide committee of students selected him as an Honorary Knight of St. Patrick because of the broad based support he showed for undergraduate students.

Addy also served as the department head for the Department of Mechanical and Industrial Engineering from 1987-1998, and during this time he had a profound impact on the department’s direction by paying close attention to the quality of education provided, research conducted, and public service completed. During his tenure, the department was consistently ranked among the best in the nation.

The support he gave to the faculty members, as well as the strong ties he built with private industry helped him aggressively pursue resources and national recognition for the department, which increased the faculty potential and accomplishments. He recognized the importance of philanthropic support for his department. Currently, 15 of the department’s faculty members hold professorships that are due in large part to Addy’s fundraising efforts.

Addy contributed to the field of engineering through work with professional societies. In 2006, he was named an honorary member of the American Society of Mechanical Engineers, which is the society’s highest honor. He is also a Fellow of the American Society for Engineering Education.