And yet it clogs: bridging of suspensions in constricted channels

From clogged arteries to clogged pipes to clogged highways, stopping the flow is always inconvenient and sometimes dangerous. Clogging is often observed in confined flows carrying either too many particles or too large particles. Clogging can be so inconvenient, necessitating lost time and labor, that we have historically worked very hard to try to prevent it. Many parameters influence the probability of clogging, such as the properties of the particles, the concentration of the suspension, and the geometry of the fluid system. It is a major issue in many engineering applications, such as additive manufacturing or bioengineering, yet our prediction of clogging of suspensions remains limited.

In this study, we consider the clogging by bridging, i.e., through the formation of a stable arch of particles at a constriction that hinders the transport of particles downstream of the clog. We characterize the role of the volume fraction of particles and of the constriction size on the lifetime of 3D-printed millifluidic devices. Our results show that for small enough constriction and for any solid fraction of particles, the clogging of the system appears to be a matter of when rather than of if. We rationalize our results using a stochastic approach that provides guidelines to avoid clogging by bridging in constricted channels. We also report design and operating guidelines that contribute to delaying clogging in fluidic systems, thus improving the reliability of many engineering systems.