Abstract
The onset of transient turbulence in plane Couette flow is identified as a homoclinic tangency with respect to a simple edge state for the Navier-Stokes equation, i.e., the gentle periodic orbit found by Kawahara & Kida (J. Fluid Mech., vol. 449, 2001, pp. 291-300). The tangency of a pair of distinct homoclinic orbits is numerically discovered at the critical Reynolds number Re ≡ Uh/ν = 241.3 (U, h, and ν being half the difference of the two wall velocities, half the wall separation, and the kinematic viscosity of fluid, respectively) above which transversal homoclinic points appear on the Poincar´e section to generate a transient chaos through a Smale horseshoe.
