title: Folded edge of turbulence in a pipe.
abstract: The results of an experimental investigation into the threshold boundary between laminar and disordered pipe flow are presented. Complex features have been uncovered using a highly refined experimental approach where an intermediate periodic state forms an integral part of the transition sequence. In accord with the suggestions produced by a numerical investigation, the boundary is found to be folded with a complicated structure. This raises important questions about accepted definitions of threshold amplitudes in this long-standing problem.
authors.affiliation: Hokkaido University, Sapporo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Tasaka
authors.forename: T M
authors.initials: TM
authors.lastname: Schneider
authors.forename: T
authors.initials: T
authors.lastname: Mullin