Numerical simulation off low past a heated/cooled sphere
Numerical simulation off low past a heated/cooled sphere
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低空加热/冷却球体的数值模拟
DOI：
10.1017/jfm.2011.517
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发表时间：
2012
影响因子：
3.7
通讯作者：
S. Komori
中科院分区：
文献类型：
--
作者：
R. Kurose;M. Anami;A. Fujita;S. Komori
通过三维数值模拟，精确考虑了密度和粘度等流体特性的温度依赖性，研究了在有浮力和无浮力条件下流经加热/冷却球体的颗粒雷诺数特性。结果表明，在无浮力的情况下，加热球和冷却球的阻力系数分别大于和小于绝热情况，其努塞尔数分别小于和大于广泛使用的努塞尔数预测经验表达式估计的值。此外，球体与环境流体之间的温差强烈影响流动分离点、球体后面涡环的尺寸以及涡流脱落的斯特劳哈尔数。这些变化归因于球体附近流体特性的温度依赖性。即使存在浮力，流体特性的温度依赖性也会强烈影响阻力系数和努塞尔数，因此随着温差的增加，布辛涅斯克近似变得不适用，无论理查森数的大小如何。
The characteristics of flow past a heated/cooled sphere are investigated for particle Reynolds numbers in conditions with and without buoyancy by means of three-dimensional numerical simulation in which temperature dependence of fluid properties such as density and viscosity is exactly taken into account. The results show that in the absence of buoyancy, drag coefficients of the heated and cooled spheres are larger and smaller than those of the adiabatic case, respectively, and their Nusselt numbers are smaller and larger than the values estimated by a widely used empirical expression for predicting Nusselt numbers, respectively. In addition, the temperature difference between the sphere and ambient fluid strongly affects the flow separation points, size of vortex ring behind the sphere and Strouhal number for vortex shedding. These changes are attributed to the temperature dependence of fluid properties in the vicinity of the sphere. Even in the presence of buoyancy, the temperature dependence of fluid properties strongly affects the drag coefficient and Nusselt number and therefore the Boussinesq approximation becomes inapplicable as the temperature difference increases, regardless of the magnitude of the Richardson number.