Instability of steady flows in helical pipes

Abstract

A parametric numerical study of three-dimensional instability of steady flows in a helical pipe of arbitrary curvature and torsion is carried out. The stability results are reported as dependences of the critical Reynolds number, critical wave number, and the critical frequency on the dimensionless pipe curvature and torsion. Patterns of several most unstable modes are reported and classified. Different routes to instability by viscous and inviscid mechanisms are discussed.