1.Introduction and motivation Dry mixing is an important process step in the production of Li-ion battery electrodes.It is not only the first process step,but also the one with significant influence on the performance...1.Introduction and motivation Dry mixing is an important process step in the production of Li-ion battery electrodes.It is not only the first process step,but also the one with significant influence on the performance of the manufactured electrodes.Numerous authors show that the quality of manufactured electrodes correlate with the degree of comminution of the conductive additive carbon black(Bockholt et al.,2013;Mayer et al.,2022;Wenzel et al.,2014).展开更多
Brownian coagulation is the most important inter-particle mechanism affecting the size distribution of aerosols. Analytical solutions to the governing population balance equation （PBE） remain a challenging issue. In...Brownian coagulation is the most important inter-particle mechanism affecting the size distribution of aerosols. Analytical solutions to the governing population balance equation （PBE） remain a challenging issue. In this work, we develop an analytical model to solve the PBE under Brownian coagulation based on the Taylor-expansion method of moments. The proposed model has a clear advantage over conventional asymptotic models in both precision and efficiency. We first analyze the geometric standard deviation （GSD） of aerosol size distribution. The new model is then implemented to determine two analytic solu- tions, one with a varying GSD and the other with a constant GSD, The varying solution traces the evolution of the size distribution, whereas the constant case admits a decoupled solution for the zero and second moments, Both solutions are confirmed to have the same precision as the highly reliable numerical model, implemented by the fourth-order Runge-Kutta algorithm, and the analytic model requires significantly less computational time than the numerical approach. Our results suggest that the proposed model has great potential to replace the existing numerical model, and is thus recommended for the study of physical aerosol characteristics, especially for rapid predictions of haze formation and evolution,展开更多
This paper describes the use of overlapping grids for the calculation of flow around single and multiple-particle configurations at the micro scale. The basic equations for calculation are those for conservation of ma...This paper describes the use of overlapping grids for the calculation of flow around single and multiple-particle configurations at the micro scale. The basic equations for calculation are those for conservation of mass and momentum which are solved using a common Finite-Volume formulation. The hydrodynamic particle-particle and particle-wall interaction can be calculated by using an overlapping or Chimera grid scheme. With the grid structuring procedure it is possible to use simple and structured grids around the particles and the overall main grid geometry. The particle grids are lapped over the main grid such that they can move independently after each time step without remeshing the whole geometry. The paper gives results for the validation of the code developed for general test cases, for a rotating ellipsoid in simple shear flow, the flow around particles attached to a wall, the motion of a particle in the vicinity of a wall and some results for the flow through a packed bed configuration.展开更多
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
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 Federal Ministry of Education and Research for funding this work in the project Sim4Pro(grant number 03XP0242B)within the ProZell Cluster.
文摘1.Introduction and motivation Dry mixing is an important process step in the production of Li-ion battery electrodes.It is not only the first process step,but also the one with significant influence on the performance of the manufactured electrodes.Numerous authors show that the quality of manufactured electrodes correlate with the degree of comminution of the conductive additive carbon black(Bockholt et al.,2013;Mayer et al.,2022;Wenzel et al.,2014).
基金the Alexander von Humboldt Foundation(Grant No.1136169)the Open Foundation of State Key Laboratory of Loess and Quaternary Geology for financial supports+2 种基金the joint support of the National Natural Science Foundation of China(Grant Nos.11372299 and 11132008)the Sino-German Research Project (Grant No.GZ971)ZJNSF(Grant No.LY13E080007)
文摘Brownian coagulation is the most important inter-particle mechanism affecting the size distribution of aerosols. Analytical solutions to the governing population balance equation （PBE） remain a challenging issue. In this work, we develop an analytical model to solve the PBE under Brownian coagulation based on the Taylor-expansion method of moments. The proposed model has a clear advantage over conventional asymptotic models in both precision and efficiency. We first analyze the geometric standard deviation （GSD） of aerosol size distribution. The new model is then implemented to determine two analytic solu- tions, one with a varying GSD and the other with a constant GSD, The varying solution traces the evolution of the size distribution, whereas the constant case admits a decoupled solution for the zero and second moments, Both solutions are confirmed to have the same precision as the highly reliable numerical model, implemented by the fourth-order Runge-Kutta algorithm, and the analytic model requires significantly less computational time than the numerical approach. Our results suggest that the proposed model has great potential to replace the existing numerical model, and is thus recommended for the study of physical aerosol characteristics, especially for rapid predictions of haze formation and evolution,
文摘This paper describes the use of overlapping grids for the calculation of flow around single and multiple-particle configurations at the micro scale. The basic equations for calculation are those for conservation of mass and momentum which are solved using a common Finite-Volume formulation. The hydrodynamic particle-particle and particle-wall interaction can be calculated by using an overlapping or Chimera grid scheme. With the grid structuring procedure it is possible to use simple and structured grids around the particles and the overall main grid geometry. The particle grids are lapped over the main grid such that they can move independently after each time step without remeshing the whole geometry. The paper gives results for the validation of the code developed for general test cases, for a rotating ellipsoid in simple shear flow, the flow around particles attached to a wall, the motion of a particle in the vicinity of a wall and some results for the flow through a packed bed configuration.
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.
