AI 中文总结
该研究采用大涡模拟（LES）探究雷诺数300下多孔介质流动，明确微涡对对流换热的影响，发现其与涡脱压力不稳定性相关，还分析了二次流动不稳定性的作用，为优化多孔介质几何提供依据。
AI 中文摘要
微尺度流动结构（小于孔径）对多孔介质中湍流传热的影响尚未得到研究，本研究旨在确定微涡对湍流多孔介质流动中对流换热的影响。采用大涡模拟（LES）研究均匀多孔介质中的湍流流动，雷诺数为300。观察到对流换热特性取决于微涡是否附着于障碍物表面。努塞尔数与涡脱引发的压力不稳定性之间存在谱相关性。障碍物间收敛通道附近周期性形成高压区，引发二次流动不稳定性，产生局部逆压梯度，影响流速与对流换热。本研究针对方形和圆柱形障碍物，孔隙率为0.50和0.87的情况开展，理解影响对流换热的主导模式有助于找到多孔介质的最优几何结构。
英文摘要
The influence of microscale flow structures (smaller than the pore size) on turbulent heat transfer in porous media has not been yet investigated. The goal of this study is to determine the influence of the micro-vortices on convection heat transfer in turbulent porous media flow. Turbulent flow in a homogeneous porous medium was investigated using Large Eddy Simulation (LES) at a Reynolds number of 300. We observed that the convection heat transfer characteristics are dependent on whether the micro-vortices are attached or detached from the surface of the obstacle. There is a spectral correlation between the Nusselt number and the pressure instabilities due to vortex shedding. A secondary flow instability occurs due to high pressure regions forming periodically near the converging pathway between obstacles. This causes local adverse pressure gradient, affecting the flow velocity and convection heat transfer. This study has been performed for obstacles with shapes of square and circular cylinders at porosities of 0.50 and 0.87. Understanding the dominant modes that affect convection heat transfer can aid in finding an optimum geometry for the porous medium.
