Alan L. Kistler, age 90, died in his sleep on April 1, 2019. He is survived by his wife of 63 years, Ingeborg B. Kistler, two daughters, Lynn (Gregory Gadbois) Kistler, and Eva (George Parker) Parker, and six grandchildren. He was preceded in death by his son, Stephen, two brothers, Ronald and Jack, and his parents Lynnea B. Isaacson Kistler and John C. Kistler.Kistler was a Professor Emeritus in the Mechanical Engineering Department at Northwestern University. He received his PhD in Aeronautics from Johns Hopkins University in 1955. After serving two years in the Army, he went to the Jet Propulsion Laboratory (JPL) where he worked on problems in high speed and turbulent flows. He was a professor at Yale University from 1961-1965, before returning to JPL as manager of the Fluid Physics Section. While there, he worked on NASA instrumentation for planetary exploration. In 1969 he joined the faculty at of Northwestern's Department of Mechanical Engineering and Astronautical Sciences. Kistler was best known for his work on turbulence, particularly the Corrsin-Kistler equation, which relates stresses between turbulent and non-turbulent regimes. His other research explorations included the effect of lake breezes on pollutant dispersion, as well as the effects of cavitation on face seals. He also studied the practical limits of solar and wind energy applications, which resulted in the installation of a wind turbine at the Evanston Ecology Center.He was a long-term member of the Unitarian Church of Evanston, where he helped with the building renovation and maintenance, was treasurer for a short time, and participated in the book club and social activities. He enjoyed hiking vacations with his extended family, and traveling with his wife, Inge. He stayed active, continuing to maintain his rental property and mow his own lawn until the end.Memorial services for Alan Kistler will be held at 3:00 P.M. on Saturday, May 25th at the Unitarian Church of Evanston, 1330 Ridge Ave., Evanston. IL.