Particle aggregation and capture by walls in a particulate aerosol channel flow

A soft-sphere discrete-element method is used to examine particle aggregate formation and particle capture by walls in a laminar channel flow. Adhesive particulates have been identified as a leading cause of failure in many different microfluidic devices, including those currently being developed by different research groups for rapid biological and chemical contaminant sensing, fluid drag reduction, etc. As these microfluidic devices enter into the marketplace and become more extensively used in field conditions, the importance of particle adhesion and clogging will increasingly limit the reliability of such systems. At a larger scale, clogging of vehicle radiators by small adhesive particles is currently a major problem for construction vehicles operating in various environmental conditions and soil types. Cooling system fouling leads to the need for frequent maintenance and machine down time. Dust fouling of equipment is also of concern for potential human occupation on dusty planets, such as Mars. The paper provides a detailed investigation of the fundamental mechanics leading to adhesion of particle aggregates to channel walls, which involves a combination of aggregate capture, aggregate deformation by particle rolling, and shearing of aggregates from the wall. Cases with different adhesion potential, particle sizes, and flow Reynolds number are examined, with both single-size particles and a binary particle mixture.