Effect of poly-dispersity on the stability of agglomerates subjected to simple fluid strain fields

Abstract

A numerical investigation of agglomerate breakup is conducted. By combining the discrete element method with hydrodynamic forces, both monodisperse and polydisperse agglomerates are subjected to three types of flow field: simple, elongational and pure rotational shear. By studying the break-up process sequence in each flow type, qualitative information about the fundamental mechanisms by which deagglomeration occurs is compared between cases and with the literature. The quantitative effectiveness of simple shear and elongational flows to break-up a monodisperse agglomerate agrees well with the relevant literature. Rotational flows are found to differ fundamentally in the way in which agglomerate break-up occurs. By minimising agglomerate translation, the energy from the flow increases the agglomerated angular momentum, eventually causing failure by rupture. Shear flows with open streamlines however may convect the agglomerate away before being able to achieve breakup. Polydispersity is found to have an effect on the qualitative break-up effectiveness; however, the fundamental break-up mechanisms remain the same as for the monodisperse agglomerate.