3. Numerical method and simulation
conditions
3.1 Numerical method
The translational and rotational motion of a particle is modeled by DEM
using Newton’s second law as16:
\(m_{i}\frac{\mathrm{d}u_{i}}{\mathrm{d}t}=\sum_{j}\left(F_{\text{ij}}^{n}+F_{\text{ij}}^{s}\right)+m_{i}g\)(2)
\(I_{i}\frac{\mathrm{d}\omega_{i}}{\mathrm{d}t}=\sum_{j}{R_{i}\times F_{\text{ij}}^{s}}\)(3)
where \(u_{i}\) and \(\omega_{i}\) are the translational and angular
velocity of particle and \(m_{i}\) and \(I_{i}\) are the mass and moment
of inertia of particle . \(F_{\text{ij}}^{n}\) and \(F_{\text{ij}}^{s}\)are the normal and tangential forces acting on particle. Particle
adhesion/cohesion is considered by implementing the adhesive/cohesive
contribution into \(F_{\text{ij}}^{n}\) and \(F_{\text{ij}}^{s}\)through JKR theory17 and the Thornton and Yin
model18,19.