Laminar natural convection in a square cavity with 3D random roughness elements considering the compressibility of the fluid
Laminar natural convection in a square cavity with 3D random roughness elements considering the compressibility of the fluid
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DOI：
10.1016/j.ijheatmasstransfer.2021.121248
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发表时间：
2021-07
影响因子：
5.2
通讯作者：
Boqi Ren;Chung-Gang Li;M. Tsubokura
中科院分区：
文献类型：
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作者：
Boqi Ren;Chung-Gang Li;M. Tsubokura
本文对瑞利数为106的三维方腔中的自然对流进行了数值研究。考虑实际情况，粗糙度生成使用一个给定的功率谱密度，并建立了一个可压缩的求解器与预处理，使用双时间步长方法来处理自然对流的低速。与不可压缩基准解决方案相比，可压缩求解器的平均努塞尔数方面表现出令人满意的精度。但是，可压缩和不可压缩求解器的局部努塞尔数结果不同。随着两侧壁温差的增大，局部努塞尔数的最大值增大，但在下游区域，局部努塞尔数反而减小。具有粗糙侧壁的空腔具有与在光滑空腔的情况下的热侧壁的平均Nusselt数相似的Nusselt数。由于粗糙度对热边界层和速度边界层的影响，在上游区域，粗糙腔的换热性能优于光滑腔，但在下游区域，粗糙腔的换热性能却比光滑腔差。
Natural convection in a three-dimensional square cavity with random artificial roughness on both vertical walls is studied numerically for a Rayleigh number of 106. Based on consideration of realistic conditions, the roughness is generated using a given power spectrum density, and a compressible solver with preconditioning that uses a dual time-stepping method is established to handle the low velocity of the natural convection flow. The compressible solver demonstrates satisfactory accuracy in terms of the average Nusselt number when compared with incompressible benchmark solutions. However, the results for the local Nusselt number from the compressible and incompressible solvers differ. As the temperature difference between the two vertical sidewalls increases, the maximum value of the local Nusselt number increases, but in the downstream region, the local Nusselt number actually decreases. The cavity with rough sidewalls has a similar Nusselt number to the average Nusselt number of a hot sidewall in the case of a smooth cavity. Because of the effects of the roughness on the thermal and velocity boundary layers, the rough cavity case shows a better heat transfer performance than the smooth cavity case in the upstream region, but in the downstream region, the heat transfer in the rough case becomes worse than that in the smooth case.