Symmetries of fluid dynamics with polytropic exponent

Abstract

The symmetries of the general Euler equations of fluid dynamics with polytropic exponent are determined using the Kaluza-Klein type framework of Duval et $\it{al}$. In the standard polytropic case the recent results of O'Raifeartaigh and Sreedhar are confirmed and generalized. Similar results are proved for polytropic exponent $\gamma=-1$, which corresponds to the dimensional reduction of $d$-branes. The relation between the duality transformation used in describing supernova explosion and Cosmology is explained.Comment: 10 pages, LaTex, no figures. Revised version: A new proof of the Schrodinger symmetry and two more references added. To appear in Phys. Lett.