Effect of particle wettability on particle-particle adhesion of colliding particles through droplet

Abstract

In wet granulation processes, a liquid bridge formed between particles is not static but dynamic due to continuous motion of the particles. Therefore, understanding of the particle-particle adhesion by a dynamic liquid bridge is an important issue. We here conducted a direct numerical simulation of the particle-particle adhesion by a dynamic liquid bridge. The particle-particle adhesion of two colliding particles through a droplet on a particle surface was simulated. In particular, effect of particle wettability on a critical velocity for the particle adhesion (i.e., adhesiveness of the two colliding particles) was investigated. It was found that the critical velocity for the particle adhesion non-monotonically changed with the particle wettability. The critical velocity exhibited a local maximum with an increase in the contact angle, while the static liquid bridge force monotonically decreases with an increase in the contact angle. We revealed that a combined effect of the liquid bridge deformation and instantaneous liquid bridge force results in the non-monotonic dependence on the particle wettability.