论文标题
评估局部各向同性，kolmogorov常数和基于涡流湍流通道流动的基于涡流粘度的建模
Assessment of local isotropy, Kolmogorov constant, and modified eddy viscosity-based modeling for particle-laden turbulent channel flows
论文作者
论文摘要
基于局部各向同性的假设，已经开发了许多解决粒子湍流动力学的模型，并使用Kolmogorov常数将湍流动能的光谱分布与湍流耗散率相关联。许多湍流模型（随机模型和LES模型）在配方中使用Kolmogorov常数。大量不同流量配置的实验数据的汇编表明，kolmogorov常数与雷诺数在高雷诺数的极限中无关（Sreenivasan，1995）。但是，在低和中间雷诺数的几项数值研究解决了实际重要性的流动情况，认为Kolmogorov常数无论流量是单相还是多相，kolmogorov常数保持不变。在目前的工作中，我们评估流体波动的局部各向同性的变化，随着颗粒含量的湍流通道流的颗粒载荷增加。我们还使用二阶速度结构函数和雷诺数低湍流的二阶速度结构函数和补偿光谱估算了kolmogorov常数。我们的研究表明，在此处研究的雷诺数范围内，Kolmogorov常数在通道中心的降低，颗粒体积分数的增加。 Kolmogorov常数的估计变化用于表达Smagorinsky系数，这是载有颗粒的流中固体载荷的函数。然后，使用大型涡流模拟（LES）采用了一种新的建模技术来预测流体相统计，而无需求解同时粒子相方程。这种新方法还有助于了解临界颗粒体积负荷下的湍流强度的急剧下降。
A large number of models which address the dynamics of particle-laden turbulent flows have been developed based on the assumption of local isotropy and use the Kolmogorov constant that correlates the spectral distribution of turbulent kinetic energy with the turbulent dissipation rate. Many turbulence models (Stochastic and LES models) use the Kolmogorov constant in the formulation. Compilation of a large number of experimental data for different flow configurations has revealed that the Kolmogorov constant is independent of Reynolds number in the limit of high Reynolds number (Sreenivasan, 1995). However, several numerical studies at low and intermediate Reynolds numbers which address the flow situations of practical importance consider that the Kolmogorov constant remains unchanged irrespective of whether the flow is single phase or multiphase. In the present work, we assess the variation of local isotropy of fluid fluctuations with the increase in particle loading in particle-laden turbulent channel flows. We also estimate the Kolmogorov constant using second-order velocity structure functions and compensated spectra in case of low Reynolds number turbulent flows. Our study reveals that the Kolmogorov constant decreases in the channel center with an increase in the particle volume fraction for the range of Reynolds number investigated here. The estimated variation of the Kolmogorov constant is used to express the Smagorinsky coefficient as a function of solid loading in particle-laden flows. Then, a new modeling technique is adopted using the large eddy simulation (LES) to predict the fluid phase statistics without solving simultaneous particle phase equations. This new methodology also helps understand the drastic decrease in turbulence intensity at critical particle volume loading.
