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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

EFFECTS OF NUMERICAL DISTURBANCES ON NATURAL CONVECTION HEAT TRANSFER FROM AN UPWARD-FACING HORIZONTAL HEATED PLATE

Get access (open in a dialog) DOI: 10.1615/IHTC16.cov.022661
pages 2847-2853

Resumo

Natural convection heat transfer from an upward-facing horizontal heated plate to stagnant surrounding air is investigated by a series of direct numerical simulations. The Rayleigh number based on the plate length and the temperature difference between the plate and the ambient fluid is 108. The difference between the present configuration and the classic Rayleigh-Benard convection is the absence of a cold cover plate and the finiteness of the plate dimension. In the present numerical simulation, the three-dimensional development of the fluid flow over the heated plate is triggered by artificial spanwise disturbances of the plate surface temperature at the immediate vicinity of the end of the plate. The disturbances are given by a single pattern of pseudo-random numbers. The amplitude of the disturbance is changed from 5 to 50 percent of the total temperature difference between the plate and the ambient fluid. The width of the band where the disturbance is imposed is 0.1 and 1 percent of the plate length. The results show that the Nusselt number is more affected by the amplitude of the disturbance than the width of the strip within a parameter range of the present study except for large amplitude case. The broader the strip is, the shorter the distance from the edge of the plate to where a pair of three-dimensional counter-rotating vortices appears for large amplitude case. This early three-dimensional development of the flow field results in enhancement of the local heat transfer.