Effects of Buoyancy on Flow Bifurcation and Heat Transfer in Three-Dimensional Plane Symmetric-Sudden Expansion


Simulations of three-dimensional laminar mixed convection in a vertical duct with plane symmetric sudden expansion are presented to illustrate the effects of the buoyancy assisting force on flow bifurcation and heat transfer. The stable laminar bifurcated flow regime that develops in this geometry at low buoyancy levels leads to non-symmetric temperature and heat transfer distributions in the transverse direction, but symmetric distributions with respect to the center width of the duct in the spanwise direction. As the buoyancy force increases, due to increases in wall heat flux, flow bifurcation diminishes and both the flow and the thermal fields become symmetric at a critical wall heat flux. The size of the primary recirculation flow region adjacent to the sudden expansion increases on one of the stepped walls and decreases on the other stepped wall as the wall heat flux increases. The maximum Nusselt number that develops on one of the stepped walls in the bifurcated flow regime is significantly larger than the one that develops on the other stepped wall. The critical wall heat flux increases as the duct's aspect ratio increases for fixed Reynolds number. The maximum Nusselt number that develops in this bifurcated flow regime increases as the duct's aspect ratio increases for fixed wall heat flux and Reynolds number.

Meeting Name

13th International Heat Transfer Conference (2006: Aug. 13-18, Sydney, Australia)


Mining Engineering

Second Department

Mechanical and Aerospace Engineering

Keywords and Phrases

Buoyancy; Flow Bifurcation; Heat Flux; Heat Transfer; Primary Recirculation Flow Region; Symmetric Sudden Expansion

Document Type

Article - Conference proceedings

Document Version


File Type





© 2006 Begell House, All rights reserved.

Publication Date

01 Jan 2006

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