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 th is paper, the mechanisms leading to chaos for a cylinder within a loos e circular support are investigated. Of particular interest is the int ermittency transition to chaos that has been found to arise. For a 2 d egree-of-freedom (d.o.f.) system, it is found that type III intermitte ncy results from destabilization of a simple (period-1) limit cycle at the onset of impacting, but the switching mechanism may also play a r ole. 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 impact ing, chaos is via the switching mechanism; at the higher flow velociti es, similarly to the 2 d.o.f. system, type I intermittency results, al beit from the destabilization of a period-2 orbit. The baker's transfo rmation is shown to make some qualitative predictions of the dynamical behaviour of the reduced Poincare map.