Irregular wavy flow due to viscous stratification

Abstract
By use of the strong surface-tension approximation, an asymptotic equation is derived to describe the nonlinear evolution of the disturbed interface in viscosity stratified-Poiseuille flow : Φτ + ΦΦ ξ + Φξξ + Φξξξξ = 0. While fully deterministic, this equation is capable of generating solutions in the form of irregularly self-fluctuating quasi-periodic waves