Brøns, Morten2; Voigt, Lars Peter Køllgaard3; Sørensen, Jens Nørkær4
1 Department of Mathematics, Technical University of Denmark2 Department of Applied Mathematics and Computer Science, Technical University of Denmark3 Department of Mechanical Engineering, Technical University of Denmark4 Department of Wind Energy, Technical University of Denmark
Using a combination of bifurcation theory for two-dimensional dynamical systems and numerical simulations, we systematically determine the possible flow topologies of the steady vortex breakdown in axisymmetric flow in a cylindrical container with rotating end-covers. For fixed values of the rotation rate of the covers in the range from -0.02 to 0.05, bifurcations of recirculating bubbles under variation of the aspect ratio of the cylinder and the Reynolds number are found. Bifurcation curves are determined by a simple fitting procedure of the data from the simulations. For the much studied case of zero rotation rate a complete bifurcation diagram is constructed. Very good agreement with experimental results is obtained, and hitherto unresolved details are determined in the parameter region where up to three bubbles exist. For non-zero rotation rates the bifurcation diagrams are found to change dramatically and give rise to other types of bifurcations.