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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

DYNAMICS OF LARGE SCALE FLOW AND ITS EFFECT ON HEAT TRANSFER IN TURBULENT CONVECTION

Get access (open in a dialog) DOI: 10.1615/IHTC16.cov.023932
pages 3589-3596

Résumé

We present direct numerical simulation performed in a cubic cell of aspect-ratio unity for air (Pr = 0:7) in the Rayleigh number range 106Ra ≤ 2 × 107. The flow structure shows the presence of large scale flow also termed as mean wind at all the Rayleigh numbers. The second invariant of the strain tensor is used to characterize the structures of the large scale flow. The vertical velocity and temperature measured at the eight probes placed in the middle of the plane near the side walls indicate the vertical plane containing the large scale flow is aligned along one of the diagonal direction of the box. Over the course of time the plane containing large scale flow switches to other diagonal. The switching of the plane of the large scale flow between the diagonals is intermittent in nature and appears to be chaotic in time. The observed structure, plane orientation along the diagonal and the dynamics of the large scale flow are consistent with the earlier experimental observations in the cubic box.