Atmospheric Research ( IF 5.5 ) Pub Date : 2021-04-20 , DOI: 10.1016/j.atmosres.2021.105634 Zhuorui Wei , Hongsheng Zhang , Yan Ren , Qianhui Li , Xuhui Cai , Yu Song , Ling Kang
In this study, the integral and microscopic turbulent statistical characteristics of pressure fluctuations, applicability of the pressure gradient and pressure flux divergence to the Monin-Obukhov similarity theory (MOST), and contribution of the pressure transport term to turbulence kinetic energy (TKE) were analyzed using the turbulence observational data obtained from a field observational station over the Horqin Sandy Land in Inner Mongolia, China. The normalized standard deviations of the pressure fluctuations have no obvious relationship with the dimensionless stability parameter (z/L). The turbulent variance spectra of pressure fluctuations Sp(n) follow the n−2 scaling law with a peak frequency of approximately one to two orders of magnitude lower than that of the wind speed and temperature. The spectral gap also shifts to lower frequencies, and the transition from turbulent scale to the larger scale is sharper. The normalized vertical pressure gradient () has no significant relationship with z/L. The non-dimensional pressure transport term () represents the pressure flux divergence and is well related to the z/L with expressions of φp = ± (1 − 14.5z/L) for unstable stratifications and φp = ± (1 + 15.0z/L) for stable stratifications. The relative importance of pressure transport term in the TKE budget equation with respect to the shear production and buoyancy terms is larger at larger scales. The pressure transport term is averagely one order of magnitude larger than the sum of these two terms at scales above 5 min. The contribution of the pressure transport term to the TKE is non-negligible.
中文翻译:
压力波动特征及其对湍流动能的影响研究
在这项研究中,压力波动的整体和微观湍流统计特征,压力梯度和压力通量散度对莫宁-奥布霍夫相似性理论(MOST)的适用性以及压力传输项对湍流动能(TKE)的贡献是使用从内蒙古科尔沁沙地上的野外观测站获得的湍流观测数据进行分析。压力波动的归一化标准偏差与无量纲稳定性参数(z / L)没有明显关系。压力波动S p(n)的湍流方差谱遵循n -2比例定律,其峰值频率比风速和温度的峰值频率低大约一到两个数量级。频谱间隙也移至较低的频率,并且从湍流标度到较大标度的过渡更加尖锐。归一化垂直压力梯度()与z / L无显着关系。无量纲压力传递项()表示压力通量散度和良好相关ž /大号带的表达式φ p =±(1 - 14.5 ž /大号不稳定分层和)φ p =±(1 + 15.0 Ž /大号),用于稳定分层。在TKE预算方程中,相对于剪力生产和浮力项,压力输运项的相对重要性更大。在5分钟以上的尺度下,压力传递项平均比这两个项的总和大一个数量级。压力传输项对TKE的贡献不可忽略。