Direct numerical simulation of flow around a heated/cooled isolated sphere up to a Reynolds number of 300 under subsonic to supersonic conditions
Direct numerical simulation of flow around a heated/cooled isolated sphere up to a Reynolds number of 300 under subsonic to supersonic conditions
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DOI：
10.1016/j.ijheatmasstransfer.2017.12.042
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发表时间：
2018-05
影响因子：
5.2
通讯作者：
T. Nagata;T. Nonomura;Shun Takahashi;Y. Mizuno;K. Fukuda
中科院分区：
文献类型：
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作者：
T. Nagata;T. Nonomura;Shun Takahashi;Y. Mizuno;K. Fukuda
在这项研究中，一个孤立的球周围的流动特性的分析等温条件下的高马赫数和低雷诺数的流动进行通过直接数值模拟（DNS）的三维可压缩Navier-Stokes方程。用边界拟合坐标系进行计算。基于球体直径和自由湍流量的雷诺数在100至300之间变化，自由湍流马赫数在0.3至2.0之间变化，球体表面和自由湍流之间的温度比在0.5至2.0之间变化。重点研究了马赫数和温度比对流动特性的影响。结果表明：（1）非定常涡从球体脱落得到促进（2）阻力系数随温度比的增大而增大，但以往的阻力关系式不能很好地预测温度比对连续区阻力系数的影响;（3）在亚音速条件下，如果温度比接近于1，则可以应用以前研究中提出的努塞尔数关系;（4）在所研究的范围内，几种流动性质的变化可以用分离点来表征。
In this study, an analysis of the flow properties around an isolated sphere under isothermal conditions for flows with high Mach numbers and low Reynolds numbers is conducted via direct numerical simulation (DNS) of the three-dimensional compressible Navier–Stokes equations. The calculations are performed with a boundary-fitted coordinate system. The Reynolds number based on the diameter of the sphere and the freestream quantities is varied from 100 to 300, the freestream Mach number is varied between 0.3 and 2.0, and the temperature ratio between the sphere surface and the freestream is varied between 0.5 and 2.0. We focus on the effects of the Mach number and the temperature ratio on the flow properties. The results show the following characteristics: (1) unsteady vortex shedding from the sphere is promoted (suppressed) when the temperature ratio is less (greater) than unity; (2) the drag coefficient increases with the temperature ratio, but previous drag relations give poor prediction on effect of the temperature ratio on the drag coefficient in the continuum regime; (3) Nusselt number relations proposed in previous studies can be applied if the temperature ratio is close to unity under subsonic conditions; (4) the changes in several flow properties can be characterized by a separation point in the range investigated.