Flow transitions in natural convection

 

Passive heat dissipation relying upon natural convection is employed in several engineering fields, including electronic, nuclear, and civil. As a matter of fact, buoyancy-induced flows offer remarkable advantages with respect to machine-driven ones, the main of which resides in being power supply free. The present project aims at investigating the case of a heated cylinder horizontally positioned inside an isothermal cavity. The configuration of a cylindrical heat source confined within an enclosure has recently aroused a growing interest, for two main reasons: firstly, many technological applications can be modeled in such a way, and secondly, the characterization of the phenomena governing the transition to chaos is simpler here than in other kind of buoyancy-induced flows. In particular, the flow transitions leading to chaos are shown to be repeatable, whereas in other convective systems (e.g., the Rayleigh-Bénard systems) these are strongly dependent on the initial conditions.

 

The goal of the project is to characterize the heat and mass transfer within the cavity, with a particular focus on the patterns of flow that the system exhibits across the different flow regimes. As a secondary objective, results will be compared with numerical predictions from a home-made code developed by the University of Modena and Reggio Emilia, to allow its validation. Measurement techniques will include: hot-wire anemometry, Particle Image Velocimetry (PIV), and thermocouples. An integral part of the project will be the design and the construction of an experimental set-up, where the leading parameter of the problem (i.e. the Rayleigh number) and the geometric configuration of the case under study (e.g., the position of the cylinder) can be varied.

 

References:

  1. Bergé P., Pomeau Y., and Vidal C., Order within chaos. Towards a deterministic approach to turbulence. Editeurs des sciences et des arts, 1984.

  2. Labonia G., and Guj G., Natural convection in a horizontal concentric cylindrical annulus: oscillatory flow and transition to chaos, Journal of Fluid Mechanics 375 (1998) 179-202.

  3. Angeli D. et al., Routes to chaos in confined thermal convection arising from a cylindrical heat source, Chaotic modelling and simulation 1 (2011) 61-68.

 

Contact:

Daniele Fiscaletti, d.fiscaletti@tudelft.nl

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