In this work the authors simulate a contaminant transport problem in three dimensions that takes place in the soil of waste disposals. Such problem is modeled by a diffusion-dominated equation. The solution of this eq...In this work the authors simulate a contaminant transport problem in three dimensions that takes place in the soil of waste disposals. Such problem is modeled by a diffusion-dominated equation. The solution of this equation is addressed by using mixed finite element method for the spatial discretization of the equation. The resulting linear algebraic system is handled by an iterative domain decomposition procedure. This procedure is naturally parallelizable, and permits to implement computational codes in distributed memory machines in order to save on CPU time. Numerical results of the serial and parallel codes were compared with experimental results, and their performance measures were evaluated. The results indicate that the parallelizable procedure is an efficient tool for performing simulations of the problem.展开更多
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
文摘In this work the authors simulate a contaminant transport problem in three dimensions that takes place in the soil of waste disposals. Such problem is modeled by a diffusion-dominated equation. The solution of this equation is addressed by using mixed finite element method for the spatial discretization of the equation. The resulting linear algebraic system is handled by an iterative domain decomposition procedure. This procedure is naturally parallelizable, and permits to implement computational codes in distributed memory machines in order to save on CPU time. Numerical results of the serial and parallel codes were compared with experimental results, and their performance measures were evaluated. The results indicate that the parallelizable procedure is an efficient tool for performing simulations of the problem.
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.
