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Turbulence Heat and Mass Transfer 6. Proceedings of the Sixth International Symposium On Turbulence Heat and Mass Transfer
September, 14-18, 2009, Rome, Italy

DOI: 10.1615/ICHMT.2009.TurbulHeatMassTransf


ISBN Print: 978-1-56700-262-1

ISSN: 2377-2816

Transition to chaos of air under conditions near the critical Rayleigh-Bénard convection in rectangular cavity

page 11
DOI: 10.1615/ICHMT.2009.TurbulHeatMassTransf.2430
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SINOPSIS

The flows are driven by the buoyancy force, which is due to the presence of gravity and density variations, from low layer to upper layer. When the temperature difference is small, the fluid is stationary. As the temperature difference is increased, the flow motion appears and is originally steady and of laminar regime. As Ra is increased beyond the first critical Rayleigh number Ra1, either periodic, or chaotic motion of fluid can be observed.
The objective is to explore when and how the instability of Rayleigh-Bénard convection with increase Ra values in the rectangular cavity. The time-dependent governing equations are solved by using the fractional step method. The time-advancement sequence is treated using the second-order Adams-Bashforth scheme, while the spatial discretization is made by the second-order QUICK scheme. The problem to be investigated is the Rayleigh-Bénard convection in three dimensions under the formulation without any approximations.
The cavity flows at Ra = 104 is steady, laminar. As Ra is increased to 5×105 the first bifurcation appears and, flow is periodic (limit cycle). As Ra is further increasing to 107 or more. The flows becomes chaotic (weakly turbulent) motion in some regions of the cavity.

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