Multiple Solutions in Fluid Mechanics
  The principle of multiple solutions of the Navier-Stokes equations discussed in this paper is not directed at any particular problems in fluid dynamics, nor at any specific applications. The non-uniqueness principle states that the Reynolds number, above its critical value, is insufficient to uniquely determine a flow field for a given geometry, or for similar geometries. It is a generic principle for all fluid flow and its transportation properties, but is not well understood. It compliments the current popular bifurcation theories by the fact that multiple solutions can exist on each stable bifurcation branch. 
Lun-Shin Yao