Characterization of Dispersive Fluxes in Mesoscale Models Using LES of Flow over an Array of Cubes
Characterization of Dispersive Fluxes in Mesoscale Models Using LES of Flow over an Array of Cubes
复制标题
使用立方体阵列上流的 LES 表征中尺度模型中的色散通量
DOI：
--
复制
发表时间：
2013
期刊：
影响因子：
--
通讯作者：
D. Robinson
中科院分区：
文献类型：
--
作者：
A. Rasheed;D. Robinson
实地研究表明，当地气候受到城市结构的强烈影响。这会影响能源消耗和行人舒适度。因此，能够模拟城市环境以在建筑和城市设计中考虑这些影响是有用的。但出于计算原因，传统的计算流体动力学 (CFD) 代码无法直接在足够精细的网格上使用来解析城市中发现的所有尺度。为此，我们使用介观模型，这是 CFD 代码的变体，其中 3D 守恒方程在分辨率为几公里的网格上求解。在此分辨率下，子网格尺度的影响需要隐式表示。换句话说，中尺度网格上平均动量和能量交换等现象为相应方程提供了必要的源/汇。这种空间平均产生了称为色散通量的附加项。到目前为止，这些通量一直被忽略。为了更好地理解这些通量，我们对不同立方体间距的立方体阵列进行了大涡模拟 (LES)。研究表明，这些通量与湍流通量一样重要，并且表现出与冠层内涡流形成相关的趋势。
Field studies have shown that local climate is strongly influenced by urban structures. This influences both energy consumption and the pedestrian comfort. It is thus useful to be able to simulate the urban environment to take these effects into account in building and urban design. But for computational reasons, conventional computational fluid dynamics (CFD) codes cannot be used directly on a grid fine enough to resolve all scales found in a city. For this, we use mesoscale models, variants of CFD codes in which the 3D conservation equations are solved on grids having a resolution of a few kilometers. At this resolution, the effects of subgrid scales need implicit representations. In other words, phenomena such as momentum and energy exchanges averaged over the mesoscale grid contribute necessary sources/sinks to the corresponding equations. Such spatial averaging results in additional terms called dispersive fluxes. Until now these fluxes have been ignored. To better understand these fluxes, we have conducted large eddy simulations (LESs) over an array of cubes for different inter-cube spacings. The study shows that these fluxes are as important as the turbulent fluxes and exhibit trends which are related to the eddy formations inside the canopies.