Scaling granular material with polygonal particles in discrete element modeling

Despite advancements in computational resources,the discrete element method(DEM)still requires considerable computational time to solve detailed problems,especially when it comes to the large-scale models.In addition to the geometry scale of the problem,the particle shape has a dramatic effect on the computational cost of DEM.Therefore,many studies have been performed with simplified spherical particles or clumps.Particle scaling is an approach to increase the particle size to reduce the number of particles in the DEM.Although several particle scaling methods have been introduced,there are still some disagreements regarding their applicability to certain aspects of problems.In this study,the effect of particle scalping on the shear behavior of granular material is explored.Real granular particles were scanned and imported as polygonal particles in the direct shear test.The effect of particle size distri-bution,particle angularity,and the amount of scalping were investigated.The results show that particle scalping can simulate the correct shear behavior of the model with significant improvement in computational time.Also,the accuracy of the scalping method depends on the particle angularity and particle size range.

Influence of Dodecyl Trimethylammonium Chloride on the Structure and Properties of Konjac Glucanmannan

This study presents the interaction between konjac glucanmannan（KGM） and cationic surfactant dodecyl trimethylammonium chloride（DTAC） to provide theoretical guidance and prediction for the experimental design and application of this composite system. Dissipative particle dynamics（DPD） method was used to simulate the interaction between KGM and the cationic surfactant. Influences of concentration, temperature and shear process on the structure and properties of aggregates were mainly examined. The results revealed that the density peak increased with the increase of concentration of KGM. With increasing the temperature, density peak moved to the right and increased, and then decreased when the temperature rose to a certain value. The density peak moved to the right at the low shear rate while decreased at the high one. During simulation, the high viscosity related to the low diffusion rate, which made it difficult to form a large continuous phase.

An advanced evaluation of the mechanistic scale-up methodology of gas-solid spouted beds using radioactive particle tracking

We implemented for the first time our radioactive particle tracking as an advanced noninvasive tech- nique to further evaluate and validate our newly developed mechanistic scale-up methodology based on matching the radial profile of the gas holdup.Two spouted beds with diameters of 0.076 and 0.152 m were used. Three sets of conditions were implemented; i.e., conditions of the reference case, conditions that provided a gas-holdup radial profile similar to that of the reference case, and conditions that provided a gas-holdup radial profile dissimilar to that of the reference case. The results confirm the validation of the scale-up methodology in terms of obtaining closer dimensionless values and radial profiles of compo- nents of the particle velocity, normal stress, shear stress, and turbulent kinetic energy, The results further advance the understanding of gas-solids spouted beds, provide deeper insight into the solids dynamics of the beds and present important benchmarking data for validating computational fluid dynamics codes and models.