The shape of particles has a significant influence on the behavior of suspensions,as the particle-fluid,particle-particle,and particle-wall interactions depend on it.However,the simultaneous consideration of complex p...The shape of particles has a significant influence on the behavior of suspensions,as the particle-fluid,particle-particle,and particle-wall interactions depend on it.However,the simultaneous consideration of complex particle shapes and four-way coupling remains a major challenge.This is mainly due to a lack of suitable contact models.Contact models for complex shapes have been proposed in literature,and most limit the accuracy of the particle-fluid interaction.For this reason,this paper presents a novel contact model for complex convex particle shapes for use with partially saturated methods,in which we propose to obtain necessary contact properties,such as the indentation depth,by a discretization of the contact area.The goal of the proposed model is to enable comprehensive and accurate studies of particulate flows,especially with high volume fractions,that lead to new insights and contribute to the improvement of existing industrial processes.To ensure correctness and sustainability,we validate the model extensively by studying cases with and without fluid.In the latter case,we use the homogenized lattice Boltzmann method.The provided investigations show a great agreement of the proposed discrete contact model with analytical solutions and the literature.展开更多
Using direct numerical simulation, we investigate the coagulation behavior of non-Brownian colloidal particles as exemplified by Al2O3 particles. This yields the so-called capture efficiency, for which we give an anal...Using direct numerical simulation, we investigate the coagulation behavior of non-Brownian colloidal particles as exemplified by Al2O3 particles. This yields the so-called capture efficiency, for which we give an analytical expression, as well as other time-dependent variables such as the cluster growth rate. Instead of neglecting or strongly approximating the hydrodynamic interactions between particles, we include hydrodynamic and non-hydrodynamic interactions in a Stokesian dynamics approach and a comprehensive modeling of the interparticle forces. The resulting parallelized simulation framework enables us to investigate the dynamics of polydisperse particle systems composed of several hundred particles at the same high level of modeling we used for a close investigation of the coagulation behavior of two unequal particles in shear flow. Appropriate cluster detection yields all the information about large destabilizing systems, which is needed for models used in flow-sheet simulations. After non-dimensionalization, the results can be generalized and applied to other systems tending to secondary coagulation展开更多
An alternative approach to simulating arbitrarily shaped particles submersed in viscous fluid in two dimensions is proposed, obtained by adapting the velocity parameter of the equilibrium distribution function of a st...An alternative approach to simulating arbitrarily shaped particles submersed in viscous fluid in two dimensions is proposed, obtained by adapting the velocity parameter of the equilibrium distribution function of a standard lattice Boltzmann method （LBM）. Comparisons of exemplifying simulations to results in the literature validate the approach as well as the convergence analysis. Pressure fluctuations occurring in Ladd＇s approach are greatly reduced. In comparison with the immersed boundary method, this approach does not require cost intensive interpolations. The parallel efficiency of LBM is retained. An intrinsic momentum transfer is observed during particle-particle collisions. To demonstrate the capa- bilities of the approach, sedimentation of particles of several shapes is simulated despite omitting an explicit particle collision model.展开更多
基金The research leading to these results was conducted during the IGF Project AiF 21096 N of the FEI that has been supported via AiF within the programme for promoting the Industrial Collective Research(IGF)of the Federal Ministry of Economic Affairs and Climate Action(BMWK)based on a resolution of the German Parliament.
文摘The shape of particles has a significant influence on the behavior of suspensions,as the particle-fluid,particle-particle,and particle-wall interactions depend on it.However,the simultaneous consideration of complex particle shapes and four-way coupling remains a major challenge.This is mainly due to a lack of suitable contact models.Contact models for complex shapes have been proposed in literature,and most limit the accuracy of the particle-fluid interaction.For this reason,this paper presents a novel contact model for complex convex particle shapes for use with partially saturated methods,in which we propose to obtain necessary contact properties,such as the indentation depth,by a discretization of the contact area.The goal of the proposed model is to enable comprehensive and accurate studies of particulate flows,especially with high volume fractions,that lead to new insights and contribute to the improvement of existing industrial processes.To ensure correctness and sustainability,we validate the model extensively by studying cases with and without fluid.In the latter case,we use the homogenized lattice Boltzmann method.The provided investigations show a great agreement of the proposed discrete contact model with analytical solutions and the literature.
文摘Using direct numerical simulation, we investigate the coagulation behavior of non-Brownian colloidal particles as exemplified by Al2O3 particles. This yields the so-called capture efficiency, for which we give an analytical expression, as well as other time-dependent variables such as the cluster growth rate. Instead of neglecting or strongly approximating the hydrodynamic interactions between particles, we include hydrodynamic and non-hydrodynamic interactions in a Stokesian dynamics approach and a comprehensive modeling of the interparticle forces. The resulting parallelized simulation framework enables us to investigate the dynamics of polydisperse particle systems composed of several hundred particles at the same high level of modeling we used for a close investigation of the coagulation behavior of two unequal particles in shear flow. Appropriate cluster detection yields all the information about large destabilizing systems, which is needed for models used in flow-sheet simulations. After non-dimensionalization, the results can be generalized and applied to other systems tending to secondary coagulation
文摘An alternative approach to simulating arbitrarily shaped particles submersed in viscous fluid in two dimensions is proposed, obtained by adapting the velocity parameter of the equilibrium distribution function of a standard lattice Boltzmann method （LBM）. Comparisons of exemplifying simulations to results in the literature validate the approach as well as the convergence analysis. Pressure fluctuations occurring in Ladd＇s approach are greatly reduced. In comparison with the immersed boundary method, this approach does not require cost intensive interpolations. The parallel efficiency of LBM is retained. An intrinsic momentum transfer is observed during particle-particle collisions. To demonstrate the capa- bilities of the approach, sedimentation of particles of several shapes is simulated despite omitting an explicit particle collision model.
