Karman Vortices in the Flow of Drag-reducing Polymer Solutions

THE effect on flow properties of adding small quantities of soluble polymers, which are able to change turbulence and form solutions of a different structure, has been reviewed 1 . Aqueous solutions of polyethylene oxide exhibit viscoelastic properties immediately after the solute has dissolved, but these disappear on ageing. The solution, however, retains its capacity for reducing turbulent resistance of friction in flow near a smooth surface for a long time, although shear flow of the solution accelerates considerably the disappearance of this capacity. Aqueous solutions of the polymer Guar gum do not display continuum viscoelastic properties, but additions of it do reduce turbulent frictional resistance.