On the Calculation of Van der Waals Force between Clay Particles

Complex physical-chemical interactions between clay particles including the van der Waals force control the macroscopic behaviors of clay. The calculation of van der Waals force is essential in the discrete element method (DEM) that has been widely used to enhance the understanding of the behavior of clay. Due to its high computational efficiency, a plate-wall model developed in the literature was adopted to obtain the van der Waals force between the neighboring clay particles approximately in the published DEM simulations. However, different choices of the ideal wall result in different magnitudes as well as directions of total van der Waals forces. To investigate the effect, a new rigorous plate-plate model was put forward and solved using an optimized Cotes integration method. Based on the comparison between the calculated results based on plate-wall and plate-plate model, the above effect was analyzed for the cases of face-face, edge-edge and edge-face contact types. Then, necessary advice for the reasonable use of the ideal-wall model was given accordingly.