An improved and efficient DEM-CFD approach is developed for spouted beds. A nonlinear Discrete Element Method （DEM）, with a concept of spring, dash-pot and friction slider, is used for tracing the movement of each i...An improved and efficient DEM-CFD approach is developed for spouted beds. A nonlinear Discrete Element Method （DEM）, with a concept of spring, dash-pot and friction slider, is used for tracing the movement of each individual particle. The gas flow is described by a set of reorganized governing equations. Two phases are coupled through contributions due to effects of porosity, viscosity and drag. All equations are solved with the commercial package Fluent with an implementation of User Defined Functions （UDF）. To validate the improved model, a two-dimensional conical-base spouted bed is chosen as a case study. An unstructured mesh system is adopted instead of regular grid system. The simulation also takes the Saffman force and Magnus effect into account. The calculation results show good agreement with the experimental observations which are taken from the literature.展开更多
The Arlequin framework proposed by Ben Dhia in 1998 is a flexible and robust method for conducting global/local analysis of structures and materials.A penalty version of the Arlequin framework for the study of structu...The Arlequin framework proposed by Ben Dhia in 1998 is a flexible and robust method for conducting global/local analysis of structures and materials.A penalty version of the Arlequin framework for the study of structural problems involving large deformation is considered here.The implementation of the penalty-based Arlequin framework into ABAQUS is then explored and the corresponding Arlequin user element subroutine is developed.Geometric nonlinear simulations of a cantilever beam and a shallow arch are conducted and the choice of the coupling operator with an appropriate penalty parameter is studied.The numerical results justify the feasibility of the proposed method,ensuring its further application to more complicated problems involving geometric or material nonlinearities.展开更多
文摘An improved and efficient DEM-CFD approach is developed for spouted beds. A nonlinear Discrete Element Method （DEM）, with a concept of spring, dash-pot and friction slider, is used for tracing the movement of each individual particle. The gas flow is described by a set of reorganized governing equations. Two phases are coupled through contributions due to effects of porosity, viscosity and drag. All equations are solved with the commercial package Fluent with an implementation of User Defined Functions （UDF）. To validate the improved model, a two-dimensional conical-base spouted bed is chosen as a case study. An unstructured mesh system is adopted instead of regular grid system. The simulation also takes the Saffman force and Magnus effect into account. The calculation results show good agreement with the experimental observations which are taken from the literature.
基金Project supported by the National Natural Science Foundation of China (No. 10725210)the National Basic Research Program (973) of China (No. 2009CB623200)
文摘The Arlequin framework proposed by Ben Dhia in 1998 is a flexible and robust method for conducting global/local analysis of structures and materials.A penalty version of the Arlequin framework for the study of structural problems involving large deformation is considered here.The implementation of the penalty-based Arlequin framework into ABAQUS is then explored and the corresponding Arlequin user element subroutine is developed.Geometric nonlinear simulations of a cantilever beam and a shallow arch are conducted and the choice of the coupling operator with an appropriate penalty parameter is studied.The numerical results justify the feasibility of the proposed method,ensuring its further application to more complicated problems involving geometric or material nonlinearities.
