Hisashi Okamoto (岡本 久, Okamoto Hisashi, born 23 November 1956) is a Japanese applied mathematician, specializing in mathematical fluid mechanics and computational fluid dynamics. Okamoto graduated from the University of Tokyo in March 1979. In April 1981 he became a research associate to Hiroshi Fujita (known for the Fujita-Kato theorem) at the University of Tokyo. There in 1985 he received his Doctorate of Science with Fujita as advisor. For the academic year 1986–1987 Okamoto was a Visiting Fellow at the University of Minnesota's Institute for Mathematics and Its Applications. In August 1987 Okamoto became an associate professor in the University of Tokyo's Department of Applied Science. In 1988 he visited the National University of Singapore. At Kyoto University's Research Institute for