Intermittency transition to chaos in the response of a loosely supported cylinder in an array in cross-flow

Cylinder arrays in heat exchangers exhibit complex dynamical behaviour when fluid excitation results in impacting with loose supports. In this paper, the mechanisms leading to chaos for a cylinder within a loose circular support are investigated. Of particular interest is the intermittency transition to chaos that has been found to arise. For a 2 degree-of-freedom (d.o.f.) system, it is found that type III intermittency results from destabilization of a simple (period-1) limit cycle at the onset of impacting, but the switching mechanism may also play a role. At higher flow velocities, a subcritical bifurcation of a period-1 orbit leads to type I intermittency. For a high-dimensional system, two mechanisms leading to chaos are identified. At the onset of impacting, chaos is via the switching mechanism; at the higher flow velocities, similarly to the 2 d.o.f. system, type I intermittency results, albeit from the destabilization of a period-2 orbit. The bakerʹs transformation is shown to make some qualitative predictions of the dynamical behaviour of the reduced Poincaré map.