And yet it clogs: flow (or no-flow) of suspensions in constricted channels
Alban Sauret, University of California Santa BarbaraAbstract:From pipes, to highways, to arteries, stopping the flow is always inconvenient and sometimes dangerous. Clogging can occur whenever a suspension, comprised of discrete particles dispersed in a liquid, flows through a confined geometry. It is a major issue in many engineering systems, such as additive manufacturing, filters, or in bioengineering. In this talk, I will discuss the role of the different clogging mechanisms and our recent efforts to characterize and model the clogging of millifluid and microfluidic systems.I will first show that clogging by bridging of non-cohesive particles, i.e., through the formation of a stable arch at a constriction, is primarily controlled by the constriction width and the volume fraction of the suspension. Our experiments can be rationalized using a stochastic approach and provide guidelines to avoid clogging by bridging in constricted channels. In a second part, I will report how pulsatile flows can help mitigate clogging when compared to steady flows in microfluidic systems. In this case, the colloidal particles can attach to the wall and eventually leads to clogging. Yet, by combining flow rate measurements with direct visualizations at the pore scale, I will describe how pulsations can delay (or not) the clogging of the system.Even if clogging may always occur in a fluid system, understanding the mechanisms and conditions of clog formation can lead to new design principles and to improve the reliability of many engineering systems.
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