Numerical and experimental investigation of the stability of the 3D flow between two counter-rotating disks

This paper is devoted to a numerical and experimental study of the 3D flow in a cylindrical cavity of large radius-to-height aspect ratio whose top and bottom lids are rotating in opposite directions. This counter rotation gives rise to a new type of instability pattern, referred as negative spirals. Comparisons between numerical and experimental results give evidence that a free shear layer instability is responsible for this new pattern.