The direct numerical simulation methodology was employed to analyze the unsteady features of a three-dimensional separated flow and heat transfer around a downward step in a rectangular channel, and to clarify systematically the channel expansion ratio effects upon them. Numerical calculations were carried out using the finite difference method. The Reynolds number Re based on the mean velocity at inlet and the step height was varied from 300 to 1000. The channel expansion ratio ER is 1.5, 2.0 and 3.0 under a step aspect ratio of 36.0. It is found that the flow is steady upto Re = 500 but becomes sensibly unsteady at Re = 700 for all the three expansion ratios. In the case of ER = 2.0, the separated shear layer is most unstable. In the case of ER = 1.5, the longitudinal vortices formed near the side walls of channel are strongest. Nusselt number reaches its maximum in the reattachment flow region and also in the neighborhood of the side wall, and their locations depend greatly upon ER and Re.
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ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems
July 17–22, 2005
San Francisco, California, USA
Conference Sponsors:
- Heat Transfer Division and Electronic and Photonic Packaging Division
ISBN:
0-7918-4733-0
PROCEEDINGS PAPER
DNS of Expansion Ratio Effects on Three-Dimensional Unsteady Separated Flow and Heat Transfer Around a Downward Step Available to Purchase
Kazuaki Sugawara,
Kazuaki Sugawara
Tohoku University, Sendai, Japan
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Hiroyuki Yoshikawa,
Hiroyuki Yoshikawa
Tohoku University, Sendai, Japan
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Terukazu Ota
Terukazu Ota
Tohoku University, Sendai, Japan
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Aya Kito
Tohoku University, Sendai, Japan
Kazuaki Sugawara
Tohoku University, Sendai, Japan
Hiroyuki Yoshikawa
Tohoku University, Sendai, Japan
Terukazu Ota
Tohoku University, Sendai, Japan
Paper No:
HT2005-72180, pp. 479-487; 9 pages
Published Online:
March 9, 2009
Citation
Kito, A, Sugawara, K, Yoshikawa, H, & Ota, T. "DNS of Expansion Ratio Effects on Three-Dimensional Unsteady Separated Flow and Heat Transfer Around a Downward Step." Proceedings of the ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems. Heat Transfer: Volume 3. San Francisco, California, USA. July 17–22, 2005. pp. 479-487. ASME. https://doi.org/10.1115/HT2005-72180
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