R. M. Kiehn "Instability Patterns, Wakes and Topological Limit Sets" in J.P.Bonnet and M.N. Glauser, (eds) "Eddy Structure Identification in Free Turbulent Shear Flows" Kluwer Academic Publishers (1993) p. 363
Abstract: Many hydrodynamic instability patterns can be put into
correspondence with a subset of characteristic surfaces of tangential
discontinuities. These topological limit sets to systems of hyperbolic PDE's
are locally unstable, but a certain subset associated with minimal surfaces are
globally stabilized, persistent and non-dissipative. Sections of theses
surfaces are the spiral scrolls so often obesrved in hydrodynamic wakes. This
method of wake production does not depend upon viscosity.