title: Knotted streamtubes in incompressible hydrodynamical flow and a restricted conserved quantity.
abstract: For certain families of fluid flow, a conserved quantity--stream helicity--has been conjectured. Using examples of linked and knotted streamtubes, it has been shown that stream helicity does, in certain cases, entertain itself with a very precise topological meaning, viz., a measure of the degree of knottedness or linkage of stream tubes. As a consequence, stream helicity may emerge as a robust topological invariant.
authors.affiliation: S.N. Bose National Centre for Basic Sciences, Saltlake, Kolkata 700098, India. sagar@bose.res.in
authors.forename: Sagar
authors.initials: S
authors.lastname: Chakraborty