Gas flows with helical surfaces of the level

Some properties of the invariant gas-dynamic submodel of rank 2 with spiral surfaces of the level are reported. Invariant and isobaric solutions of the submodel are considered. Institute of Mechanics, Ufa Scientific Center, Russian Academy of Sciences, Ufa 450000. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No. 2, pp. 34–39, March–April, 1999.