Experimental study of the multipolar vortex instability
Résumé
The instability of a vortex subject to a stationary dipolar or tripolar constraint is studied experimentally using a rotating deformable cylinder on which two or three rolls are applied. As the Reynolds number and the aspect ratio of the cylinder are varied, different modes of instability are observed and their wavelength and frequency are compared to theoretical predictions. Secondary instability and cyclic break up are also evidenced in the elliptic geometry.