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ISSN Online: 2377-424X

ISBN Print: 1-56032-797-9

International Heat Transfer Conference 11
August, 23-28, 1998, Kyongju, Korea

THE EFFECT OF FORCED FLOW ON TURBULENT NATURAL CONVECTION ADJACENT TO A VERTICAL BACKWARD-FACING STEP

Get access (open in a dialog) DOI: 10.1615/IHTC11.3160
pages 269-274

Resumo

Turbulent mixed convection adjacent to a two dimensional, vertical backward-facing step is predicted numerically to explore the effect of forced flow velocity on turbulent natural convection. A two-equation k-ε turbulence model is utilized in the numerical simulation. Computations are performed for air with a Prandtl number of 0.71 for a step height of 2.2 cm and a temperature difference of 30°C between the heated upstream and downstream plates and the free stream. The effects of increasing the forced flow velocity on the reattachment length, the local Nusselt number, the mean velocity and temperature distributions, the turbulent kinetic energy and its dissipation rate are examined. The computational results have revealed that the introduction of small forced flow velocities (0.1°1.0 m/s) to an existing turbulent natural convection flow suppresses the turbulence intensity, decreases the heat transfer rate from the wall, and delays the transition location from laminar to turbulent flow. An interesting feature is that the turbulent natural convection flow changes from buoyancy-dominated turbulent mixed convection to laminar mixed convection and that is followed by turbulent forced convection as the forced flow velocity increases beyond 1.0 m/s.