Published online by Cambridge University Press: 24 June 2011
The transition from two-dimensional to three-dimensional flows in a finite circular cylinder driven by an axially oscillating sidewall is explored in detail. The complete symmetry group of this flow, including a spatio-temporal symmetry related to the oscillating sidewall, is Z2 × O(2). Previous studies in flows with the same symmetries, such as symmetric bluff-body wakes and periodically forced rectangular cavities, were unable to obtain the theoretically predicted bifurcation to modulated travelling waves. In the simpler cylindrical geometry, where the azimuthal direction is physically periodic, we have found these predicted modulated travelling waves as stable fully saturated nonlinear solutions for the first time. A careful analysis of the base states and their linear stability identifies different parameter regimes where three-dimensional states are either synchronous with the forcing or quasi-periodic, corresponding to different symmetry-breaking processes. These results are in good agreement with theoretical predictions and previous results in similar flows. These different regimes are separated by three codimension-two bifurcation points that are yet to be fully analysed theoretically. Finally, the saturated nonlinear states and their properties in different parameter regimes are analysed.
Movie 1a: Animation of the streamfunction of the basic state at $St=10$ and $Re=340$. The left boundary is the cylinder axis and the right boundary is the axially-oscillating cylinder sidewall. Solid (dashed) contours are positive (negative); yellow/red colors correspond to negative/positive values. Movies 1a-h correspond to figure 2 in the paper.
Movie 1a: Animation of the streamfunction of the basic state at $St=10$ and $Re=340$. The left boundary is the cylinder axis and the right boundary is the axially-oscillating cylinder sidewall. Solid (dashed) contours are positive (negative); yellow/red colors correspond to negative/positive values. Movies 1a-h correspond to figure 2 in the paper.
Movie 2a: Animation of isosurfaces of radial vorticity (solid) and of azimuthal vorticity (translucent) for the synchronous state $B_1$ at $St=10$ and $Re=340$. Movies 2a-c correspond to figure 6 in the paper.
Movie 2a: Animation of isosurfaces of radial vorticity (solid) and of azimuthal vorticity (translucent) for the synchronous state $B_1$ at $St=10$ and $Re=340$. Movies 2a-c correspond to figure 6 in the paper.
Movie 3a: Animation of isosurfaces of radial vorticity (solid) and of azimuthal vorticity (translucent) for the quasi-periodic state $MRW_1$ at $St=50$ and $Re=615$. Movies 3a and b correspond to figure 10 in the paper.
Movie 3a: Animation of isosurfaces of radial vorticity (solid) and of azimuthal vorticity (translucent) for the quasi-periodic state $MRW_1$ at $St=50$ and $Re=615$. Movies 3a and b correspond to figure 10 in the paper.
Movie 4a: Same as in movie 3a, but strobed once per period. Movies 4a and b correspond to figure 11 in the paper.
Movie 4a: Same as in movie 3a, but strobed once per period. Movies 4a and b correspond to figure 11 in the paper.
Movie 2b: Same as in movie 2a, but for the synchronous state $B_2$ at $St=32$ and $Re=525$.
Movie 2b: Same as in movie 2a, but for the synchronous state $B_2$ at $St=32$ and $Re=525$.
Movie 3b: Same as in movie 3a, but for the quasi-periodic state $MSW_1$ at the same point in parameter space. Movies 3a and b correspond to figure 10 in the paper.
Movie 3b: Same as in movie 3a, but for the quasi-periodic state $MSW_1$ at the same point in parameter space. Movies 3a and b correspond to figure 10 in the paper.
Movie 2c: Same as in movie 2a, but for the synchronous state $A_2$ at $St=100$ and $Re=700$.
Movie 2c: Same as in movie 2a, but for the synchronous state $A_2$ at $St=100$ and $Re=700$.
Movie 1e: Same as in movie 1a, but showing the azimuthal component of vorticity.
Movie 1e: Same as in movie 1a, but showing the azimuthal component of vorticity.
Movie 1f: Same as in movie 1b, but showing the azimuthal component of vorticity.
Movie 1f: Same as in movie 1b, but showing the azimuthal component of vorticity.
Movie 1g: Same as in movie 1c, but showing the azimuthal component of vorticity.
Movie 1g: Same as in movie 1c, but showing the azimuthal component of vorticity.