Liquid Transport in Bi-disperse Particle Beds revealed by Direct Numerical Simulations

Flow of highly saturated wet granular matter is encountered in wide range of engineering application, particularly in the pharmaceutics, food industry and energy sector, in addition, granular particles beds usually compose of various of particle properties (i.e.,, shape, size, density, etc.) and it well know that particle size polydispersity and shape significantly influence on the transport of mass and liquid in a fluidized bed system , therefore the better understanding of these systems (i.e., bi-and polydisperse particle system) aid on improving control of such engineering applications. However, it is still a big challenge to scale and characterize such particle systems because liquid transport and exchange of liquid volume on particle surfaces is in such systems usually rather complicated.
In this paper, we study the liquid transport between particles of different sizes, as well as build a dynamic liquid bridge model to predict liquid transport between these two particles. Specifically, the drainage process of liquid adhering to two unequally-sized, non-porous wet particles with difference initial film heights is simulated using Direct Numerical Simulations (DNS). Same as in our previous work4, we first provide an analytical solution of a proposed dynamic liquid bridge model. We find that such an analytical solution also describes liquid transport during collisions of unequally-sized particles very well. Finally, we show that our proposed model structure is sufficient to collapse all our direct numerical simulation data, and hence is able to predict liquid transport rates in these systems for a wide range of parameters.