Experimental Evidence of a Nonlinear Transition from Convective to Absolute Instability
Résumé
We report both experimentally and analytically a transition from a convective to an absolute regime for a Kelvin-Helmholtz unstable sheared interface between two fluids in parallel flow in a Hele- Shaw cell. Experimental evidence is obtained by measurements from both sides of this transition, via two independent tests. The results are in good agreement with the nonlinear transition recently described in a theoretical analysis [Couairon and Chomaz, Physica (Amsterdam) 108D, 236 (1997)]. [S0031-9007(99)08489-6]