Study on the Subgrid Scale Modeling for Particle-Laden Turbulent Flows

含颗粒湍流亚网格尺度建模研究

基本信息

批准号：
09650189
负责人：
KAJISHIMA Takeo
金额：
$ 2.11万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650189/
关键词：
Turbulent Flow Multiphase Flow Multiphase Turbulence Gas-Liquid Two Phase Flow Direct Numerical Simulation Large-Eddy Simulation Subgrid Scale Model Computational Fluid Dynamics

项目摘要

We carried out a direct numerical simulation (DNS) of fluid-solid two-phase turbulent flows to consider the subgrid scale (SGS) modeling in the large-eddy simulation (LES) of particle-laden turbulence.First, we developed a finite-difference scheme to resolve the interaction between fluid turbulence and particle motion.In our method, the flow around a solid particle having a length scale several times larger than the spacing of computational grid, is directly simulated.The particle motion is governed by the surface integral of pressure and viscous stress together with the body force such as gravity.This scheme includes no models in fluid turbulence, particle motion or interaction between them.Then, we examined our new method by applying it to the three-dimensional flow past a sphere fixed in a uniform stream.As for the drag coefficient as well as the unsteady vortex shedding, numerical results agreed with experimental results.When the vortex shedding took place, turbulence energy induce … More d through wake was not fully dissipated in the region near a particle.This non-equilibrium nature was enhanced just after the change in drag force of a particle.Next, we simulated a forced isotropic turbulence and turbulent flow in a plane channel including sphere particles.Particles formed larger structure such as clusters, resulting in an additional scale of energy source for fluid turbulence.In an another setup, the relative position of particles was fixed to observe the turbulence modulation without particle clusters.In this case, total energy was sometimes reduced due to the shift of energy spectra into high wavenumber range, even though particles induced extra.In the wall turbulence, particles were distributed non-uniformly in the channel.In this case, the shed vortices was stretched into the streamwise direction due to the velocity gradient, resulted in the production of Reynolds shear stress.These DNS results of particle-laden turbulent flows suggested some important characteristics to be accounted for in SGS modeling.They are non-equilibrium nature due to unsteady vortex shedding, multiple scale of energy injection to fluid turbulence, the modulation in turbulence length scale by particle distribution, and the Reynolds stress production due to the stretch of shed vortices, for example. Less

我们对流体 - 固定的两相湍流流进行了直接数值模拟（DNS），以考虑在富含粒子的湍流的大涡模拟（LES）中的亚网格量表（SGS）模型。直接模拟了计算网格。颗粒运动受压力和粘性压力以及重力等体力的表面组成的控制。该方案不包括流体湍流，粒子运动或它们之间的相互作用模型。与实验结果达成一致。当涡旋脱落发生时，湍流能量会引起湍流……在粒子附近附近的区域并未完全消散。这种非平衡性质在粒子的阻力变化后，增强了这种非平衡性质。next的变化后，我们模拟了较大的粒子，包括较大的粒子，包括较大的范围。流体湍流的来源。在另一种设置中，固定颗粒的相对位置以观察没有颗粒簇的湍流调节。在这种情况下，由于能量光谱向高波数范围的转移，有时还会降低总能量，即使粒子诱导了额外的颗粒，颗粒在壁液中均不均匀地分布在湍流中，因此在这种情况下分布了均匀的方向。梯度，导致雷诺的产生剪切应力。这些DNS的含粒子湍流的结果提出了在SGS建模中要考虑的一些重要特征。它们是由于不稳定的涡旋脱落，流体湍流的多尺度能量注入，湍流长度尺度的调节量以及雷诺因脱落涡流而引起的雷诺压力产生，它们是非平衡性质。较少的