Flow reversal of laminar mixed convection in the entry region of symmetrically heated, vertical plate channels

• Published in: International journal of thermal sciences Vol. 48; no. 11; pp. 2036 - 2045
• Main Authors: Desrayaud, Gilles, Lauriat, Guy
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Masson SAS 01.11.2009; Elsevier
• Subjects: Convection and heat transfer; Engineering Sciences; Exact sciences and technology; Flow reversal; Flows in ducts, channels, nozzles, and conduits; Fluid dynamics; Fundamental areas of phenomenology (including applications); Mechanics; Mixed convection; Numerical heat transfer; Physics; Thermics; Turbulent flows, convection, and heat transfer; Vertical channel; Numerical heat transfer; Vertical channel; Mixed convection; Flow reversal; Temperature distribution; Vertical pipe; Digital simulation; Boundary conditions; Velocity distribution; Combined convection; Reversed flow; Laminar flow; Modelling; Heat transfer; Parallel plate
• ISSN: 1290-0729; 1778-4166
• DOI: 10.1016/j.ijthermalsci.2009.03.002

The present numerical investigation is concerned with flow reversal phenomena for laminar, mixed convection of air in a vertical parallel-plate channel of finite length. Results are obtained for buoyancy-assisted flow in a symmetrically heated channel with uniform wall temperatures for various Grashof numbers and Reynolds numbers in the range 300 ≤ Re ≤ 1300. The effects of buoyancy forces on the flow pattern are investigated and the shapes of velocity and temperature profiles are discussed in detail. Flow reversals centred in the entrance of the channel are predicted. The strength of the cells decreases as the Reynolds number is increased, until they disappear. The regime of reversed flow is identified for high values of the Péclet number in a Pe–Gr/Re map. It is also shown that the channel length has no influence on the occurrence of the reversal flow provided that H/ D ≥ 10.