School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, 150001, China.
Nanoscale Res Lett. 2013 Feb 4;8(1):56. doi: 10.1186/1556-276X-8-56.
Considering interaction forces (gravity and buoyancy force, drag force, interaction potential force, and Brownian force) between nanoparticles and a base fluid, a two-phase Lattice Boltzmann model for natural convection of nanofluid is developed in this work. It is applied to investigate the natural convection in a square enclosure (the left wall is kept at a high constant temperature (TH), and the top wall is kept at a low constant temperature (TC)) filled with Al2O3/H2O nanofluid. This model is validated by comparing numerical results with published results, and a satisfactory agreement is shown between them. The effects of different nanoparticle fractions and Rayleigh numbers on natural convection heat transfer of nanofluid are investigated. It is found that the average Nusselt number of the enclosure increases with increasing nanoparticle volume fraction and increases more rapidly at a high Rayleigh number. Also, the effects of forces on nanoparticle volume fraction distribution in the square enclosure are studied in this paper. It is found that the driving force of the temperature difference has the biggest effect on nanoparticle volume fraction distribution. In addition, the effects of interaction forces on flow and heat transfer are investigated. It is found that Brownian force, interaction potential force, and gravity-buoyancy force have positive effects on the enhancement of natural convective heat transfer, while drag force has a negative effect.
考虑到纳米粒子与基液之间的相互作用力（重力和浮力、阻力、相互势能和布朗力），本文开发了一个两相格子玻尔兹曼模型来研究纳米流体的自然对流。该模型应用于研究填充有 Al2O3/H2O 纳米流体的方形腔中的自然对流（左壁保持高温（TH），顶壁保持低温（TC））。通过将数值结果与已发表的结果进行比较，对该模型进行了验证，结果表明两者吻合良好。研究了不同纳米粒子分数和瑞利数对纳米流体自然对流换热的影响。结果表明，腔的平均努塞尔数随纳米粒子体积分数的增加而增加，在高瑞利数下增加得更快。此外，本文还研究了各种力对纳米粒子在方形腔中体积分数分布的影响。结果表明，温差驱动力对纳米粒子体积分数分布的影响最大。另外，还研究了相互作用力对流动和传热的影响。结果表明，布朗力、相互势能和重力浮力对自然对流换热的增强有积极影响，而阻力则有负面影响。
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