Numerical simulation of gas-solid flow behaviors in a rectangular fluidized bed is carried out three dimensionally by the discrete element method (DEM).Euler method and Lagrange method are employed to deal with the ga...Numerical simulation of gas-solid flow behaviors in a rectangular fluidized bed is carried out three dimensionally by the discrete element method (DEM).Euler method and Lagrange method are employed to deal with the gas phase and solid phase respectively.The collided force among particles,striking force between particle and wall,drag force,gravity,Magnus lift force and Saffman lift force are considered when establishing the mathematic models.Soft-sphere model is used to describe the collision of particles.In addition,the Euler method is also used for modeling the solid phase to compare with the results of DEM.The flow patterns,particle mean velocities,particles' diffusion and pressure drop of the bed under typical operating conditions are obtained.The results show that the DEM method can describe the detailed information among particles,while the Euler-Euler method cannot capture the micro-scale character.No matter which method is used,the diffusion of particles increases with the increase of gas velocity.But the gathering and crushing of particles cannot be simulated,so the energy loss of particles' collision cannot be calculated and the diffusion by using the Euler-Euler method is larger.In addition,it is shown by DEM method,with strengthening of the carrying capacity,more and more particles can be schlepped upward and the dense suspension upflow pattern can be formed.However,the results given by the Euler-Euler method are not consistent with the real situation.展开更多
Transports of air particulate matters(PM) from face sources in the atmospheric boundary layer(ABL) are investigated by the Eulerian single fluid model and the Lagrangian trajectory method,respectively.Large eddy simul...Transports of air particulate matters(PM) from face sources in the atmospheric boundary layer(ABL) are investigated by the Eulerian single fluid model and the Lagrangian trajectory method,respectively.Large eddy simulation is used to simulate the fluid phase for high accuracy in both two approaches.The mean and fluctuating PM concentrations,as well as instantaneous PM distributions at different downstream and height positions,are presented.Higher mean and fluctuating particle concentrations are predicted by the Eulerian approach than the Lagrangian one.For the Lagrangian method,PM distributions cluster near the ground-wall because of the preferential dispersion of inertial particles by turbulence structures in the ABL,while it cannot be obtained by the Eulerian single fluid method,because the two-phase velocity differences are neglected in the Eulerian method.展开更多
基金Supported by National Natural Science Foundation of China(51006106)National High Technology Research and Development of China 863 Program(2006AA05A103)
文摘Numerical simulation of gas-solid flow behaviors in a rectangular fluidized bed is carried out three dimensionally by the discrete element method (DEM).Euler method and Lagrange method are employed to deal with the gas phase and solid phase respectively.The collided force among particles,striking force between particle and wall,drag force,gravity,Magnus lift force and Saffman lift force are considered when establishing the mathematic models.Soft-sphere model is used to describe the collision of particles.In addition,the Euler method is also used for modeling the solid phase to compare with the results of DEM.The flow patterns,particle mean velocities,particles' diffusion and pressure drop of the bed under typical operating conditions are obtained.The results show that the DEM method can describe the detailed information among particles,while the Euler-Euler method cannot capture the micro-scale character.No matter which method is used,the diffusion of particles increases with the increase of gas velocity.But the gathering and crushing of particles cannot be simulated,so the energy loss of particles' collision cannot be calculated and the diffusion by using the Euler-Euler method is larger.In addition,it is shown by DEM method,with strengthening of the carrying capacity,more and more particles can be schlepped upward and the dense suspension upflow pattern can be formed.However,the results given by the Euler-Euler method are not consistent with the real situation.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50876053 and 11132005)Opening fund of State of Key Laboratory of Nonlinear Mechanics
文摘Transports of air particulate matters(PM) from face sources in the atmospheric boundary layer(ABL) are investigated by the Eulerian single fluid model and the Lagrangian trajectory method,respectively.Large eddy simulation is used to simulate the fluid phase for high accuracy in both two approaches.The mean and fluctuating PM concentrations,as well as instantaneous PM distributions at different downstream and height positions,are presented.Higher mean and fluctuating particle concentrations are predicted by the Eulerian approach than the Lagrangian one.For the Lagrangian method,PM distributions cluster near the ground-wall because of the preferential dispersion of inertial particles by turbulence structures in the ABL,while it cannot be obtained by the Eulerian single fluid method,because the two-phase velocity differences are neglected in the Eulerian method.
