Keywords: Wirbelring.png en Vortex ring in a laminar fluid stream de Wirbelring in einer laminaren Strömung Etching from an old German textbook of physics Author Book about 1904 scan by the uploader 2011-04-14 PD-1923 Also copyright-free according to German law because of its simplicity fehlende Schöpfungshöhe missing level of creativity / treshold of originality Cc-zero Toroidal vortices Fluid dynamics |