Flow transitions around in line cylinders

The flow around aligned cylinders is an archetype for several industrial devices (rod structure of the nuclear reactors, compact heat exchangers for electronic components, pin-fins heat exchangers for micro-devices ) and environmental phenomena (diffusion process close to the vegetation). Cylinders produce instabilities in the flow structures that are very sensitive to the control parameters such as the inflow velocity, the spacing between the cylinders and the fluid viscosity. The instabilities leads the transport phenomena close to the cylinders and they affect the force, the thermal balance at their surface and the diffusion process. The strong velocity gradients in confined spaces make that the experimental analysis is difficult, while the numerical simulation appears to be a promising tool for this purpose.