Based on a semi-resolved CFD-DEM coupling method,this study proposed a method that uses the minimum distance between the fluid grid and the particle boundary as a reference value to determine the degree of influence o...Based on a semi-resolved CFD-DEM coupling method,this study proposed a method that uses the minimum distance between the fluid grid and the particle boundary as a reference value to determine the degree of influence of the target fluid grid on the particle's drag force.A fluidized bed of rod-like particles was chosen as a typical case to investigate the effect of different fluid grid scales on various fluidized bed characteristic parameters.The calculation performance of the semi-resolved and unre-solved CFD-DEM coupling algorithm on key fluidized bed characteristic parameters such as average pressure drop,particle frequency distribution with bed height,and particle orientation distribution were compared.It was found that the semi-resolved CFD-DEM coupling algorithm gradually obtained results with higher consistency with decreasing fluid grid scale for key parameters such as particle frequency distribution with bed height,particle orientation distribution,and time-history mixing index,exhibiting a phenomenon similar to grid independence in fluid simulation.By comparing with experimental results,it was verified that the semi-resolved CFD-DEM coupling algorithm can be applied to simulate multi-granular gas-solid systems with fluid grid scales equivalent to particle scales.This algorithm solves the limitation of fluid grid scale in the unresolved CFD-DEM coupling framework and improves the grid adaptability of the CFD-DEM coupling simulation algorithm.展开更多
This study develops an extended unresolved CFD-DEM coupling method for simulation of the fluid-solid flow with non-spherical particles.The limitation of fluid grid size is discussed,by simulating the settling of a cyl...This study develops an extended unresolved CFD-DEM coupling method for simulation of the fluid-solid flow with non-spherical particles.The limitation of fluid grid size is discussed,by simulating the settling of a cylinder in a Newtonian fluid based on the resolved and unresolved CFD-DEM coupling method.Then,the calculation of porosity and the fluid-particle relative velocity based on the particle shape enlarge-ment method for simulation of non-spherical particles is proposed.The availability of the particle shape enlargement method for the simulation of non-spherical particles with different sphericity is discussed in this work,by comparing it with the results from the equivalent diameter enlargement method.The lim-itation of the equivalent diameter enlargement method for non-spherical particles is revealed from the simulation results.Several typical cases are employed to elaborate and verify the extended unresolved CFD-DEM method based on particle shape enlargement method,by presenting a good consistency with the experimental results.It proves that the extended unresolved CFD-DEM method is suitable for differ-ent CFD grid size ratios,and consolidates that it is a universal calculation method for CFD-DEM coupling simulation.展开更多
基金funded by the National Natural Science Foundation of China (grant No.11972250)the National Key R&D Program of China (grant Nos.22YFE0207000 and 2022YFC3004505).
文摘Based on a semi-resolved CFD-DEM coupling method,this study proposed a method that uses the minimum distance between the fluid grid and the particle boundary as a reference value to determine the degree of influence of the target fluid grid on the particle's drag force.A fluidized bed of rod-like particles was chosen as a typical case to investigate the effect of different fluid grid scales on various fluidized bed characteristic parameters.The calculation performance of the semi-resolved and unre-solved CFD-DEM coupling algorithm on key fluidized bed characteristic parameters such as average pressure drop,particle frequency distribution with bed height,and particle orientation distribution were compared.It was found that the semi-resolved CFD-DEM coupling algorithm gradually obtained results with higher consistency with decreasing fluid grid scale for key parameters such as particle frequency distribution with bed height,particle orientation distribution,and time-history mixing index,exhibiting a phenomenon similar to grid independence in fluid simulation.By comparing with experimental results,it was verified that the semi-resolved CFD-DEM coupling algorithm can be applied to simulate multi-granular gas-solid systems with fluid grid scales equivalent to particle scales.This algorithm solves the limitation of fluid grid scale in the unresolved CFD-DEM coupling framework and improves the grid adaptability of the CFD-DEM coupling simulation algorithm.
基金funded by the National Natural Science Foundation of China(grant No.11972250)the key projects of Tianjin city(grant No.19JCZDJC32000)。
文摘This study develops an extended unresolved CFD-DEM coupling method for simulation of the fluid-solid flow with non-spherical particles.The limitation of fluid grid size is discussed,by simulating the settling of a cylinder in a Newtonian fluid based on the resolved and unresolved CFD-DEM coupling method.Then,the calculation of porosity and the fluid-particle relative velocity based on the particle shape enlarge-ment method for simulation of non-spherical particles is proposed.The availability of the particle shape enlargement method for the simulation of non-spherical particles with different sphericity is discussed in this work,by comparing it with the results from the equivalent diameter enlargement method.The lim-itation of the equivalent diameter enlargement method for non-spherical particles is revealed from the simulation results.Several typical cases are employed to elaborate and verify the extended unresolved CFD-DEM method based on particle shape enlargement method,by presenting a good consistency with the experimental results.It proves that the extended unresolved CFD-DEM method is suitable for differ-ent CFD grid size ratios,and consolidates that it is a universal calculation method for CFD-DEM coupling simulation.