Pore-scale large eddy simulation of turbulent flow and heat transfer over porous media
Pore-scale large eddy simulation of turbulent flow and heat transfer over porous media
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多孔介质湍流和传热的孔隙尺度大涡模拟
DOI：
10.1016/j.applthermaleng.2022.118916
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发表时间：
2022
影响因子：
6.4
通讯作者：
Jadidi M
中科院分区：
文献类型：
--
作者：
Jadidi M
本文采用孔洞尺度大涡模拟方法研究了孔道内多孔介质内的湍流流动与换热。特别注意了多孔区和非多孔区之间通过两个区域之间的界面进行的热量和流动的交换。为此，分析了两种不同的由球体和矩形棒填充床组成的多孔系统，并将结果与相同尺寸的固体块体情况进行了比较。流动可视化显示，进入多孔块的很大一部分流体通过多孔区-流体界面从多孔区泄漏到非多孔区。为了讨论这种流动泄漏对流动特性和换热的影响，讨论了速度场、压力场和温度场，以及相干结构和湍流产生。多孔区内的流动形态表明，渗漏堵塞了多孔介质内部的孔道，导致孔道流动的流向动量显着降低。此外，相干结构表明，流动泄漏导致在多孔区块内部和上方产生反向旋转的流体涡对，从而形成有序的发夹结构。最后，比较了多孔和固体情况下的湍流产生以及Kelvin-Helmholtz不稳定性在多孔-流体界面上的开始增长，结果表明，在多孔块体的前缘以上，湍流动能降低。这一观察结果表明，对于多孔情况，向湍流的转变被推迟到多孔块的下游，并且没有固体块实现得那么快。
This paper investigates turbulent fluid flow and heat transfer over a porous medium in a channel using pore-scale large eddy simulation. Special attention is placed on the exchange of heat and flow between the porous and non-porous regions through the interface between the two regions. For this purpose, two different porous systems made of a packed bed of spheres and rectangular rods are analysed and the results are compared against a solid block case of the same size. Flow visualization shows that a significant portion of the fluid entering the porous blocks leaks from the porous region to the non-porous region through the porous-fluid interface. To discuss the effects of this flow leakage on the flow features and heat transfer, discussions are made regarding velocity, pressure, and temperature fields, as well as coherent structures, and turbulence production. The flow pattern inside the porous region indicates that the flow leakage clogs the pore channels inside the porous medium which induces a significant reduction in the streamwise momentum of the pore flow. In addition, coherent structures show that flow leakage leads to the creation of counter-rotating vortex pairs of fluid flow within and above the porous block that results in the formation of organized hairpin structures. Finally, the comparison of turbulence production for the porous and solid cases together with the onset growth of the Kelvin-Helmholtz instability on the porous-fluid interface show a reduction in turbulent kinetic energy above the leading edge of porous blocks. This observation implies that for the porous cases the transition to turbulence is postponed to the downstream of the porous block and it is not achieved as fast as the solid block.