Particle-assisted dynamic wetting in a suspension liquid jet impinged onto a moving solid at different flow rates

We provide evidence that the introduction of solid spheres assists the dynamic wetting in suspension jet flows. The onset velocities of air entrainment in the suspension were measured and compared with those in the filler-free fluids to directly access the particle-assisted dynamic wetting. The measured onset velocity increased with increasing the particle contents at Re<20 where the dynamic contact line is located beneath the impinging liquid. The variation in the onset velocity agrees with a simple lubrication theory based on the film-splitting hypothesis. However, the onset velocities of air entrainment become independent of the particle contents at Re>20, higher liquid viscosities or increased jet lengths, showing different air entrainment behaviors from other low-Reynolds number coating flows.