Buoyancy-assisted mixed convective flow over backward-facing step in a vertical duct using nanofluids

Laminar mixed convective buoyancy assisting flow through a two-dimensional vertical duct with a backward-facing step using nanofluids as a medium is numerically simulated using finite volume technique. Different types of nanoparticles such as Au, Ag, Al2O3, Cu, CuO, diamond, SiO2 and TiO2 with 5 vo...

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Main Authors:	Mohammed, H.A., Al-Aswadi, A.A., Yusoff, M.Z., Saidur, R.
Format:	Article
Published:	Thermophysics and Aeromechanics 2012
Subjects:	TA Engineering (General). Civil engineering (General) TJ Mechanical engineering and machinery
Online Access:	http://link.springer.com/article/10.1134%2FS0869864312010040 http://link.springer.com/article/10.1134%2FS0869864312010040

id	um-6287
recordtype	eprints
spelling	um-62872013-07-02T02:13:45Z Buoyancy-assisted mixed convective flow over backward-facing step in a vertical duct using nanofluids Mohammed, H.A. Al-Aswadi, A.A. Yusoff, M.Z. Saidur, R. TA Engineering (General). Civil engineering (General) TJ Mechanical engineering and machinery Laminar mixed convective buoyancy assisting flow through a two-dimensional vertical duct with a backward-facing step using nanofluids as a medium is numerically simulated using finite volume technique. Different types of nanoparticles such as Au, Ag, Al2O3, Cu, CuO, diamond, SiO2 and TiO2 with 5 volume fraction are used. The wall downstream of the step was maintained at a uniform wall temperature, while the straight wall that forms the other side of the duct was maintained at constant temperature equivalent to the inlet fluid temperature. The walls upstream of the step and the backward-facing step were considered as adiabatic surfaces. The duct has a step height of 4.9 mm and an expansion ratio of 1.942, while the total length in the downstream of the step is 0.5 m. The downstream wall was fixed at uniform wall temperature 0 a parts per thousand currency sign Delta Ta parts per thousand currency sign 30 A degrees C, which was higher than the inlet flow temperature. The Reynolds number in the range of 75 a parts per thousand currency sign Re a parts per thousand currency sign 225 was considered. It is found that a recirculation region was developed straight behind the backward-facing step which appeared between the edge of the step and few millimeters before the corner which connect the step and the downstream wall. In the few millimeters gap between the recirculation region and the downstream wall, a U-turn flow was developed opposite to the recirculation flow which mixed with the unrecirculated flow and traveled along the channel. Two maximum and one minimum peaks in Nusselt number were developed along the heated downstream wall. It is inferred that Au nanofluid has the highest maximum peaks while diamond nanofluid has the highest minimum peak. Nanofluids with a higher Prandtl number have a higher peak of Nusselt numbers after the separation and the recirculation flow disappeared. Thermophysics and Aeromechanics 2012 Article PeerReviewed http://link.springer.com/article/10.1134%2FS0869864312010040 Mohammed, H.A.; Al-Aswadi, A.A.; Yusoff, M.Z.; Saidur, R. (2012) Buoyancy-assisted mixed convective flow over backward-facing step in a vertical duct using nanofluids. Thermophysics and Aeromechanics <http://eprints.um.edu.my/view/publication/Thermophysics_and_Aeromechanics.html>, 19 (1). pp. 33-52. ISSN 0869-8643 http://eprints.um.edu.my/6287/
repository_type	Digital Repository
institution_category	Local University
institution	University Malaya
building	UM Research Repository
collection	Online Access
topic	TA Engineering (General). Civil engineering (General) TJ Mechanical engineering and machinery
spellingShingle	TA Engineering (General). Civil engineering (General) TJ Mechanical engineering and machinery Mohammed, H.A. Al-Aswadi, A.A. Yusoff, M.Z. Saidur, R. Buoyancy-assisted mixed convective flow over backward-facing step in a vertical duct using nanofluids
description	Laminar mixed convective buoyancy assisting flow through a two-dimensional vertical duct with a backward-facing step using nanofluids as a medium is numerically simulated using finite volume technique. Different types of nanoparticles such as Au, Ag, Al2O3, Cu, CuO, diamond, SiO2 and TiO2 with 5 volume fraction are used. The wall downstream of the step was maintained at a uniform wall temperature, while the straight wall that forms the other side of the duct was maintained at constant temperature equivalent to the inlet fluid temperature. The walls upstream of the step and the backward-facing step were considered as adiabatic surfaces. The duct has a step height of 4.9 mm and an expansion ratio of 1.942, while the total length in the downstream of the step is 0.5 m. The downstream wall was fixed at uniform wall temperature 0 a parts per thousand currency sign Delta Ta parts per thousand currency sign 30 A degrees C, which was higher than the inlet flow temperature. The Reynolds number in the range of 75 a parts per thousand currency sign Re a parts per thousand currency sign 225 was considered. It is found that a recirculation region was developed straight behind the backward-facing step which appeared between the edge of the step and few millimeters before the corner which connect the step and the downstream wall. In the few millimeters gap between the recirculation region and the downstream wall, a U-turn flow was developed opposite to the recirculation flow which mixed with the unrecirculated flow and traveled along the channel. Two maximum and one minimum peaks in Nusselt number were developed along the heated downstream wall. It is inferred that Au nanofluid has the highest maximum peaks while diamond nanofluid has the highest minimum peak. Nanofluids with a higher Prandtl number have a higher peak of Nusselt numbers after the separation and the recirculation flow disappeared.
format	Article
author	Mohammed, H.A. Al-Aswadi, A.A. Yusoff, M.Z. Saidur, R.
author_facet	Mohammed, H.A. Al-Aswadi, A.A. Yusoff, M.Z. Saidur, R.
author_sort	Mohammed, H.A.
title	Buoyancy-assisted mixed convective flow over backward-facing step in a vertical duct using nanofluids
title_short	Buoyancy-assisted mixed convective flow over backward-facing step in a vertical duct using nanofluids
title_full	Buoyancy-assisted mixed convective flow over backward-facing step in a vertical duct using nanofluids
title_fullStr	Buoyancy-assisted mixed convective flow over backward-facing step in a vertical duct using nanofluids
title_full_unstemmed	Buoyancy-assisted mixed convective flow over backward-facing step in a vertical duct using nanofluids
title_sort	buoyancy-assisted mixed convective flow over backward-facing step in a vertical duct using nanofluids
publisher	Thermophysics and Aeromechanics
publishDate	2012
url	http://link.springer.com/article/10.1134%2FS0869864312010040 http://link.springer.com/article/10.1134%2FS0869864312010040
first_indexed	2018-09-06T05:18:55Z
last_indexed	2018-09-06T05:18:55Z
_version_	1610834127645310976

Buoyancy-assisted mixed convective flow over backward-facing step in a vertical duct using nanofluids

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