“…The contact forces caused by particle–particle or particle-wall collisions are described using the contact models. Several contact models have been discussed in the literature, ,,, namely, elastic contact model (Hertz theory), elastic–plastic contact model, viscoelastic contact model (spring-dashpot), adhesion contact model (Johnson–Kendall–Roberts, JKR model), and tangential stiffness model (Hertz–Mindlin, H–M model). The concept of each model is described based on the elasticity, viscosity, hydrophilicity, and other related physical properties of primary NPs. , …”