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Numerical study of natural convection in a horizontal cylinder filled with water-based alumina nanofluid.

Meng X, Li Y - Nanoscale Res Lett (2015)

Bottom Line: The two solvers are used for same cases and compared to corresponding experimental results.By comparison, the average natural Nusselt numbers of water and Al2O3/water nanofluids are found to increase with the Rayleigh number.The temperature-dependent solver is found better for water and 1% Al2O3/water nanofluid cases, while the original solver is better for 4% Al2O3/water nanofluid cases.

View Article: PubMed Central - PubMed

Affiliation: Research Group of Offshore Engineering, School of Marine Science and Technology, Armstrong Building, Newcastle University, Newcastle upon Tyne, England NE1 7RU UK.

ABSTRACT
Natural heat convection of water-based alumina (Al2O3/water) nanofluids (with volume fraction 1% and 4%) in a horizontal cylinder is numerically investigated. The whole three-dimensional computational fluid dynamics (CFD) procedure is performed in a completely open-source way. Blender, enGrid, OpenFOAM and ParaView are employed for geometry creation, mesh generation, case simulation and post process, respectively. Original solver 'buoyantBoussinesqSimpleFoam' is selected for the present study, and a temperature-dependent solver 'buoyantBoussinesqSimpleTDFoam' is developed to ensure the simulation is more realistic. The two solvers are used for same cases and compared to corresponding experimental results. The flow regime in these cases is laminar (Reynolds number is 150) and the Rayleigh number range is 0.7 × 10(7) ~ 5 × 10(7). By comparison, the average natural Nusselt numbers of water and Al2O3/water nanofluids are found to increase with the Rayleigh number. At the same Rayleigh number, the Nusselt number is found to decrease with nanofluid volume fraction. The temperature-dependent solver is found better for water and 1% Al2O3/water nanofluid cases, while the original solver is better for 4% Al2O3/water nanofluid cases. Furthermore, due to strong three-dimensional flow features in the horizontal cylinder, three-dimensional CFD simulation is recommended instead of two-dimensional simplifications.

No MeSH data available.


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Comparison of Nusselt number in 4% Al2O3/water nanofluid cases.
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Fig8: Comparison of Nusselt number in 4% Al2O3/water nanofluid cases.

Mentions: In this study, natural heat convection of water and 1% and 4% Al2O3/water nanofluids is investigated numerically by both ‘buoyantBoussinesqSimpleFoam’ and ‘buoyantBoussinesqSimpleTDFoam’. For each fluid, five simulations are performed in the Rayleigh number range Ra = 107 ~ 0.8 × 108. Figures 4, 5, 6, 7 and 8 show the results of the average Nusselt number against the Rayleigh number in different cases. Basically, by both the present numerical study and previous experimental study, the natural Nusselt number of water and Al2O3/water nanofluids is found to increase with the Rayleigh number. However, some more information also can be found by further comprehensive comparisons in the present work.Figure 4


Numerical study of natural convection in a horizontal cylinder filled with water-based alumina nanofluid.

Meng X, Li Y - Nanoscale Res Lett (2015)

Comparison of Nusselt number in 4% Al2O3/water nanofluid cases.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385295&req=5

Fig8: Comparison of Nusselt number in 4% Al2O3/water nanofluid cases.
Mentions: In this study, natural heat convection of water and 1% and 4% Al2O3/water nanofluids is investigated numerically by both ‘buoyantBoussinesqSimpleFoam’ and ‘buoyantBoussinesqSimpleTDFoam’. For each fluid, five simulations are performed in the Rayleigh number range Ra = 107 ~ 0.8 × 108. Figures 4, 5, 6, 7 and 8 show the results of the average Nusselt number against the Rayleigh number in different cases. Basically, by both the present numerical study and previous experimental study, the natural Nusselt number of water and Al2O3/water nanofluids is found to increase with the Rayleigh number. However, some more information also can be found by further comprehensive comparisons in the present work.Figure 4

Bottom Line: The two solvers are used for same cases and compared to corresponding experimental results.By comparison, the average natural Nusselt numbers of water and Al2O3/water nanofluids are found to increase with the Rayleigh number.The temperature-dependent solver is found better for water and 1% Al2O3/water nanofluid cases, while the original solver is better for 4% Al2O3/water nanofluid cases.

View Article: PubMed Central - PubMed

Affiliation: Research Group of Offshore Engineering, School of Marine Science and Technology, Armstrong Building, Newcastle University, Newcastle upon Tyne, England NE1 7RU UK.

ABSTRACT
Natural heat convection of water-based alumina (Al2O3/water) nanofluids (with volume fraction 1% and 4%) in a horizontal cylinder is numerically investigated. The whole three-dimensional computational fluid dynamics (CFD) procedure is performed in a completely open-source way. Blender, enGrid, OpenFOAM and ParaView are employed for geometry creation, mesh generation, case simulation and post process, respectively. Original solver 'buoyantBoussinesqSimpleFoam' is selected for the present study, and a temperature-dependent solver 'buoyantBoussinesqSimpleTDFoam' is developed to ensure the simulation is more realistic. The two solvers are used for same cases and compared to corresponding experimental results. The flow regime in these cases is laminar (Reynolds number is 150) and the Rayleigh number range is 0.7 × 10(7) ~ 5 × 10(7). By comparison, the average natural Nusselt numbers of water and Al2O3/water nanofluids are found to increase with the Rayleigh number. At the same Rayleigh number, the Nusselt number is found to decrease with nanofluid volume fraction. The temperature-dependent solver is found better for water and 1% Al2O3/water nanofluid cases, while the original solver is better for 4% Al2O3/water nanofluid cases. Furthermore, due to strong three-dimensional flow features in the horizontal cylinder, three-dimensional CFD simulation is recommended instead of two-dimensional simplifications.

No MeSH data available.


Related in: MedlinePlus