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Nanofluid is a kind of new engineering medium which is created by dispersing small quantity of nano-sized particles in the base fluid. The dispersion of solid nanoparticles in conventional fluids changes their transport properties remarkably. Molecular dynamics simulation (MDS) is an important approach to study the transport properties of nanofluids. However, the computation amount is huge, and it is very difficult to use the normal MDS to capture the transient flow and heat processes in Cu-H2O nanofluids if the regions in the simulation reach 149.6443 nm3 or 299.2883 nm3, and the number of Cu nano-particles reaches 6-64. Further study by means of simulation on the effects on effective transport properties of nanofluids is also difficult. In this paper, the water-based fluid region of 149.6443 nm3 or 299.2883 nm3 is assumed as continuum phase because of the very low Knudsen number of fluid, and the effects of water on nano-particles are fitted into the Cu-Cu potential parameters. Using the proposed method, the computation amount is significantly reduced. The effective thermal conductivity and dynamic viscosity coefficient of Cu-H2O nanofluids under the stationary condition are simulated and the results are verified with existing experimental data. The motion and aggregation processes of nano-particles in the water-based fluids at different velocity shear rate are simulated. Effects of velocity shear rate, fluid velocity, temperature gradient, and average temperature on the effective thermal conductivity and the dynamic viscosity of Cu-H2O nanofluids in the processes of flow and heat transfer are studied. Three conclusions can be drawn from the obtained results. Firstly, the proposed method is feasible to capture the transient flow and heat processes in Cu-H2O nanofluids, and is also capable to further study the transport properties of Cu-H2O nanofluids. Secondly, the velocity shear rate acting on a nanofluid can effectively prevent the aggregating process of nano-particles, and therefore reduce the diameter of particle-aggregations. Finally, the velocity shear rate and the average temperature of Cu-H2O nanofluids have much more effects on the transport properties, while the fluid velocity and temperature gradient have less effects; the velocity shear rate increases the effective thermal conductivity of a nanofluid but decreases its dynamic viscosity. A rise of average temperature increases the effective thermal conductivity but decreases the dynamic viscosity.
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Keywords:
- nanofluids /
- molecular dynamics simulation /
- transport properties /
- aggregation
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[2] Qi C, He G Y, Li Y M, He Y R 2015 Acta Phys. Sin. 64 024703(in Chinese) [齐聪, 何光艳, 李意民, 何玉荣 2015 64 024703]
[3] Hatat T, Imtiaz M, Alsaedi A, Mansoor R 2014 Chin. Phys. B 23 054701
[4] Li Y T, Shen L P, Wang H, Wang H B 2013 Acta Phys. Sin. 62 124401(in Chinese) [李屹同, 沈谅平, 王浩, 汪汉斌 2013 62 124401]
[5] Ling Z Y, Sun D J, Zhang Z Q 2013 Journal of Functional Materials 1 92 (in Chinese) [凌智勇, 孙东健, 张忠强 2013 功能材料 1 92]
[6] Lee J, Yoon Y J, Eaton J K 2014 International Journal of Precision Engineering and Manufacturing 15 703
[7] Beydokhti A K, Namaghi H A, Heris S Z 2013 Numerical Heat Transfer, Part B: Fundamentals 64 480
[8] Khalili S, Dinarvand S, Hosseini R, Tamim H, Pop I 2014 Chin. Phys. B 23 048203
[9] Xiao B Q, Yang Y, Xu X F 2014 Chin. Phys. B 23 026601
[10] Ahmad A, Asghar S, Alsaedi A 2014 Chin. Phys. B 23 074401
[11] Frenkel D, Smit B 1996 Understanding Molecular Simulation From Algorithms to Applications(Cornwall: Academic Press) pp51-69
[12] Gianluca Puliti 2014 Ph. D. Dissertation(Indiana: University of Notre Dame)
[13] Kumar P, Varanasi S R, Yashonath S 2013 J Phys. Chem. B 117 27
[14] Chen X, Cao G X, Han A J 2008 Nano Letters 8 2988
[15] Lin Y S, Hsiao P Y, Chieng C C 2011 Applied Physics Letters 98 153105
[16] Cui W Z, Bai M L, Lv J Z, Li X J 2011 I ndustrial Engineering Chemistry Research 50 13568
[17] He Y C, Liu X J 2014 Chinese Journal of Theoretical and Applied Mechanics 46 871 (in Chinese) [何昱辰, 刘向军 2014 力学学报 46 871]
[18] Bhattacharya P, S. Saha K, Yadav A 2004 Journal of Applied physic 95 6492
[19] Melle S, Calderon O G, Rubio M A 2002 J. Non-Newtonian Fluid Mech. 102 135
[20] Klingenberg D J, Van S F, Zukoski C F 1989 J. Chem. Phys. 91 7888
[21] Hansen J P, MeDonald I R 1986 Theory of Simple Liquids (New York: Academic Press) p238-302
[22] Andry T, Jose A 1999 J. Chem. Phys. 18 8510
[23] Sarkar S, Selvam R P 2007 Journal of Applied Physics 102 074302
[24] Li Q 2003 Ph. D. Dissertation (Nanjing: Nanjing University of Science and Technology) (in Chinese) [李强 2003 博士学位论文 (南京: 南京理工大学, 2003)]
[25] Li Q, Xuan Y M 2003 Journal of Chemical Industry and Engineering 54 42 (in Chinese) [李强, 宣益民 2003 化工学报 54 42]
[26] Wang B X 2000 Heat Transfer science and Technology (Beijing: Higher Education Press) pp757-762
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[1] Xuan Y M, Li Q 2010 Energy transfer theory and application of nanofluid. (Beijing: Science Press) pp1-10 (in Chinese) [宣益民, 李强 2010 纳米流体能量传递理论与应用(北京:科学出版社) 第110页]
[2] Qi C, He G Y, Li Y M, He Y R 2015 Acta Phys. Sin. 64 024703(in Chinese) [齐聪, 何光艳, 李意民, 何玉荣 2015 64 024703]
[3] Hatat T, Imtiaz M, Alsaedi A, Mansoor R 2014 Chin. Phys. B 23 054701
[4] Li Y T, Shen L P, Wang H, Wang H B 2013 Acta Phys. Sin. 62 124401(in Chinese) [李屹同, 沈谅平, 王浩, 汪汉斌 2013 62 124401]
[5] Ling Z Y, Sun D J, Zhang Z Q 2013 Journal of Functional Materials 1 92 (in Chinese) [凌智勇, 孙东健, 张忠强 2013 功能材料 1 92]
[6] Lee J, Yoon Y J, Eaton J K 2014 International Journal of Precision Engineering and Manufacturing 15 703
[7] Beydokhti A K, Namaghi H A, Heris S Z 2013 Numerical Heat Transfer, Part B: Fundamentals 64 480
[8] Khalili S, Dinarvand S, Hosseini R, Tamim H, Pop I 2014 Chin. Phys. B 23 048203
[9] Xiao B Q, Yang Y, Xu X F 2014 Chin. Phys. B 23 026601
[10] Ahmad A, Asghar S, Alsaedi A 2014 Chin. Phys. B 23 074401
[11] Frenkel D, Smit B 1996 Understanding Molecular Simulation From Algorithms to Applications(Cornwall: Academic Press) pp51-69
[12] Gianluca Puliti 2014 Ph. D. Dissertation(Indiana: University of Notre Dame)
[13] Kumar P, Varanasi S R, Yashonath S 2013 J Phys. Chem. B 117 27
[14] Chen X, Cao G X, Han A J 2008 Nano Letters 8 2988
[15] Lin Y S, Hsiao P Y, Chieng C C 2011 Applied Physics Letters 98 153105
[16] Cui W Z, Bai M L, Lv J Z, Li X J 2011 I ndustrial Engineering Chemistry Research 50 13568
[17] He Y C, Liu X J 2014 Chinese Journal of Theoretical and Applied Mechanics 46 871 (in Chinese) [何昱辰, 刘向军 2014 力学学报 46 871]
[18] Bhattacharya P, S. Saha K, Yadav A 2004 Journal of Applied physic 95 6492
[19] Melle S, Calderon O G, Rubio M A 2002 J. Non-Newtonian Fluid Mech. 102 135
[20] Klingenberg D J, Van S F, Zukoski C F 1989 J. Chem. Phys. 91 7888
[21] Hansen J P, MeDonald I R 1986 Theory of Simple Liquids (New York: Academic Press) p238-302
[22] Andry T, Jose A 1999 J. Chem. Phys. 18 8510
[23] Sarkar S, Selvam R P 2007 Journal of Applied Physics 102 074302
[24] Li Q 2003 Ph. D. Dissertation (Nanjing: Nanjing University of Science and Technology) (in Chinese) [李强 2003 博士学位论文 (南京: 南京理工大学, 2003)]
[25] Li Q, Xuan Y M 2003 Journal of Chemical Industry and Engineering 54 42 (in Chinese) [李强, 宣益民 2003 化工学报 54 42]
[26] Wang B X 2000 Heat Transfer science and Technology (Beijing: Higher Education Press) pp757-762
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