Three dimensional thermal Lattice Boltzmann simulation of heating/cooling spheres falling in a Newtonian liquid
Three dimensional thermal Lattice Boltzmann simulation of heating/cooling spheres falling in a Newtonian liquid
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DOI：
10.1016/j.ijthermalsci.2014.03.008
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发表时间：
2014-08
影响因子：
4.5
通讯作者：
Z. Hashemi;O. Abouali;R. Kamali
中科院分区：
文献类型：
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作者：
Z. Hashemi;O. Abouali;R. Kamali
本文用数值方法研究了充液箱中小球在重力作用下的沉降传热。采用三维格子Boltzmann方法模拟流体-颗粒相互作用。首先，开发的数值模型进行了验证与实验和数值数据的比较，在一个充满液体的盒子下降的球体。在此基础上，研究了定温和变温条件下颗粒沉降的雷诺数、普朗特数和格拉肖夫数（Re、Pr、Gr）对颗粒沉降的影响。研究了沉降颗粒的速度、高度和努塞尔数随时间的变化规律。结果表明，在不同的表面温度下，颗粒的最大沉降速度在较低的雷诺数下较高。随着雷诺数的增加，恒定和变化的温度下的颗粒的沉降速度是相同的。但是，颗粒在不同温度下的努塞尔数低于颗粒在恒定表面温度下的努塞尔数。增加Grashof数会导致更慢的稳定和更大的平均努塞尔数。最后研究了30个球形热粒子在封闭空间中的沉降及其与周围流体的水力和传热相互作用。结果描述了热传递现象的存在如何显著改变沉降颗粒的行为。
This paper presents a numerical study of heat transfer from spheres settling under gravity in a box filled with liquid. Three-dimensional Lattice Boltzmann Method is applied to simulate fluid-particle interaction. Firstly the developed numerical model is validated in comparison with experimental and numerical data for a falling sphere in a box filled with liquid. Then the effects of Reynolds, Prandtl and Grashof numbers (Re,Pr,Gr) are investigated for a settling particle at fixed/varied temperature. The time variations of velocity, height and Nusselt number of the settling particle are also investigated. The results depict that the maximum settling velocity of the particle at varied surface temperature is higher at lower Reynolds numbers. As the Reynolds number increases, the settling velocity of the particle for both cases of constant and varied temperature is the same. However, the Nusselt number of the particle at varied temperature is lower compared with that for the particle at constant surface temperature. Increasing the Grashof number leads to slower settling and larger average Nusselt number. Finally sedimentation of 30 hot spherical particles in an enclosure and their hydraulic and heat transfer interactions with the surrounding fluid are studied. The results depict how the presence of heat transfer phenomena can significantly alter the behavior of settling particles.