Abstract
Comprehension of wet particle behavior is of great importance in science and engineering. In the past two decades, modeling and simulation for wet particles have been extensively studied because of their various industrial applications. The discrete element method (DEM) is extensively employed to simulate the wet particle behavior. To calculate the wet particle behavior, several capillary force models have been developed so far. Roughly speaking, the capillary force models are classified into two types, namely, the analytical model and the geometrical approximation model. The analytical model is most frequently employed because of its simplicity, though only a small amount of the liquid volume is applicable. The geometrical approximation model has significant advantages because of no theoretical limitation of the liquid volume as well as its high accuracy. Incidentally, the geometrical approximation model usually expresses the liquid bridge shape by the toroidal approximation. However, validation tests for the geometrical approximation model have hardly been performed due to difficulty in incorporating the complex algorithm into the DEM. From the background, this paper aims to prove the superiority and adequacy of the geometrical approximation model in the DEM simulation for wet particles. First, the superiority of the geometrical approximation model to the analytical model is examined in a two-body system. Afterward, the following two types of validation tests are performed: granular collapse and wet powder mixing in a twin-screw kneader. In the granular collapse, the liquid content is set to be less than 4 vol. %. In the twin-screw kneader system, the liquid content is more than 5 vol. %. Through the validation tests, the adequacy of the geometrical approximation model in the DEM is proved because of the agreement between the computational and experimental results in the above systems. Consequently, this study will significantly contribute to a better understanding of wet particle behavior in science and engineering.
Highlights
Wet particles are extensively studied in science[1,2,3,4,5,6] and engineering.[7,8,9,10,11,12,13,14] A major feature of the wet particles is the cohesive property due to the capillary force
The flexible Eulerian–Lagrangian method with an implicit (FELMI) code equips highly original models, which have been developed in the authors’ group, namely, the signed distance function (SDF)[26] for an arbitrary shape wall boundary in the discrete element method (DEM), the immersed boundary method[27–29] for an arbitrary shape wall boundary in a coupled computational fluid dynamics (CFD) and DEM, the thin wall boundary model in the CFD-DEM,[30] a gas–solid–liquid flow model,[31] the capillary force model based on the toroidal approximation,[19] the coarse-grained DEM,[32] and a multi-thread parallel computation technique.[33]
The other was due to the modeling problem that was unique to the DEM
Summary
Wet particles are extensively studied in science[1,2,3,4,5,6] and engineering.[7,8,9,10,11,12,13,14] A major feature of the wet particles is the cohesive property due to the capillary force. The capillary force, which arises from the capillary pressure, and tensile force tend to induce strong adhesive force in neighboring particles. The liquid bridge state is classified into three types, namely, pendular, funicular, and capillary. These states change by the volumetric liquid content, and they can be distinguished by the liquid content. The impact of the liquid bridges on the wet particle flow is very significant. The significant impact is because the mechanical properties and dynamic responses of the wet particles are extremely different from those of the dry powder. For a better understanding of the wet particle behavior, numerical modeling is positively employed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
