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Three-dimensional flow effects on forced convection heat transfer in a channel with stepwise-varying width

Karathanassis, I. K., Papanicolaou, E., Belessiotis, V. & Bergeles, G. (2013). Three-dimensional flow effects on forced convection heat transfer in a channel with stepwise-varying width. International Journal of Thermal Sciences, 67, pp. 177-191. doi: 10.1016/j.ijthermalsci.2012.12.016


A numerical investigation based on the finite volume methodology of the three-dimensional laminar flow and conjugate heat transfer inside a plate-fin heat sink with stepwise-varying channel width is presented. Results are obtained for the three-dimensional flow developed in the vicinity of the flow contraction as manifested by the existence of two pairs of contra-rotating longitudinal vortices, one at the corners of the fin leading edge and the other at the flow separated regions. The topology of the flow is thoroughly examined and the contributions of the endwalls and the front surface of the flow-contracting fin to the mechanisms that cause the emergence of the three-dimensionality are determined. It is established that the corner longitudinal vortices are in fact horseshoe vortices, which emerge due to the deceleration effect of the fin front surface on the oncoming fluid. Furthermore, the interaction between the corner longitudinal vortices and the downstream recirculation bubble formed over the fin tip is also elucidated. The analysis covers a wide range of flow conditions within the laminar region in order to monitor the effect of the Reynolds number on the flow topology and to verify that the flow remains symmetrical in this region. From the numerical results, it is deduced that the recirculation downstream of the flow contraction has a beneficial impact on the heat sink thermal performance, a fact quantified through the local Nusselt number distributions.

Publication Type: Article
Additional Information: © 2013. This manuscript version is made available under the CC-BY-NC-ND 4.0 license
Publisher Keywords: Flow contraction, Stepwise-varying width, Secondary flow pattern, Horseshoe vortex, Plate–fin heat sink
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
Departments: School of Science & Technology > Engineering
SWORD Depositor:
[thumbnail of THESCI-D-12-00415_Karathanassis-et-al_IntJThermSc_Clean_Version.pdf]
Text - Accepted Version
Available under License Creative Commons Attribution Non-commercial No Derivatives.

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