大尺寸颗粒与各向同性湍流双向耦合的直接数值模拟

项目名称： 大尺寸颗粒与各向同性湍流双向耦合的直接数值模拟

项目编号： No.U1230126

项目类型： 联合基金项目

立项/批准年度： 2013

项目学科： 物理学II

项目作者： 晋国栋

作者单位： 中国科学院力学研究所

项目金额： 50万元

中文摘要： 颗粒-流体二相湍流在环境和工业流动中广泛存在。大涡模拟方法在二相湍流的预测与控制中有望发挥重要作用。用欧拉-拉格朗日方法描述二相湍流，当颗粒直径大于湍流Kolmogorov 长度尺度（本申请项目称为“大”或“有限”尺寸颗粒）时，解析颗粒的直接数值模拟正成为研究颗粒与湍流相互作用及其模型构建的重要工具。 我们在本项目中以解析颗粒的直接数值模拟为工具，（1）研究颗粒直径对颗粒在各向同性衰减湍流中受力、混合和聚团的影响；（2）研究颗粒对湍流能谱标度指数的改变及颗粒引起的额外湍流耗散率，以此为基础，发展二相湍流大涡模拟亚格子应力模型和颗粒雷诺数大于1时非线性阻力公式的亚格子模型。然后，我们把所发展的亚格子模型应用于颗粒直径远小于滤波宽度的大涡模拟中进行验证。 本项目的目标是理解大尺寸颗粒与湍流双向耦合机理和发展二相湍流大涡模拟亚格子模型，提高其预测能力。

中文关键词： 湍流；二相流；混合；解析颗粒直接数值模拟；大涡模拟方法

英文摘要： Particle-laden turbulent flows are ubiquitous in nature and engineering applications. Large-eddy simulation (LES) is the most suitable approach to predict and control the two-phase turbulent flows. The mostly used point-particle model loses its ability to describe the motion of particles when the particle diameter is larger than the Kolmogorov length scale (which is termed as large-size or finite-size particle in this proposal), since the flow field induced by the particle is nonuniform at the particle scale. In order to overcome the limitations of the point-particle model, the particle-resolved Direct Numerical Simulation (DNS) has been emerging as a powerful tool to study the interactions between large-size particles and turbulence, and to formulate such interactions. In this proposal, we shall use the particle-resolved DNS (1) to study the effects of particle diameter on the statistics of the force (or acceleration PDF), mixing and preferential concentration of particles in decaying isotropic turbulent flows; (2) to study the variations in the scaling exponents of the energy spectrum and the additional turbulent energy dissipation rate due to the suspended particles, then to develop a subgrid scale model to account for the subgrid stress and a second subgrid model to account for the nonlinear drag force c

英文关键词： Turbulent flows；Two-Phase Flows；Mixing；Particle-Resolved Direct Numerical Simulation；Large-eddy Simulation