Felix Issidorowitsch Frankl (12 March 1905, Vienna – 7 Aprile 1961, Nalchik Russian: Феликс Исидорович Франкль) was an Austrian mathematician, who went to live in the Soviet Union where he had an academic career as a university professor.
[1] He studied topology at the Faculty of Mathematics of the University of Vienna under Hans Hahn, gaining his doctorate in 1927.
His interests then shifted to certain particular differential equations which are important for high-speed aerodynamics.
They determined the transition in aerodynamics between transonic and supersonic speeds.
[3] In 1957 he was awarded the Leonhard Euler Gold Medal of the Russian Academy of Sciences.