Numerical simulation of clogging in a microchannel with planar contraction

Abstract

Clogging is the mechanism that interrupts the flow in confined geometries due to the complete blockage of the channel cross section. It represents a critical issue in the processing of particle suspensions for both industrial and biological applications, and it is particularly relevant in microfluidics and membrane technology due to the high particle confinement and the difficult device cleaning. Although numerous experimental and numerical studies have been carried out to understand the mechanism governing this complex multiscale phenomenon, the picture is not yet clear and many questions still remain, especially at the particle level. In this regard, the numerical simulations may represent a useful investigation tool since they provide a direct insight to quantities not easily accessible from experiments. In this work, a detailed computational fluid dynamics-discrete element method simulation study on the clogging mechanism in a microchannel with planar contraction is carried out. Both constant flow rate and constant pressure drop conditions are investigated, highlighting the effect of flow conditions, particle volume fraction, cohesion forces, and contraction angle. The onset of clogging conditions is discussed.

Flow dynamics through discontinuous clogs of rigid particles in tapered microchannels

“…Results presented in Ref. 15 for a single non-tapered channel shows Q ∽ t −1 in the period intervening the initial clog formation and decay end time. However, as shown in Eq.…”

“…13,45 define τ g as the mean interval between two clogging events. In a single non-tapered channel, it was measured as the time required for a decrease in the initial suspension flowrate by 10% 15 . Both types of experimentally measured timescales match the prediction from the steady-state flux balance in Eq.…”

“…Barring differences in τ d , the collapse of the flowrate decays into a single curve (Fig. 3a) suggests φ impacts the magnitude of clogging only, and not necessarily the clogging mechanism 15 . Since the channels are of finite volume, there is a maximum number of particles that can effectively pack into them, regardless of φ .…”

“…Each microchannel has a uniform rectangular cross section coupled to a smaller constriction at the outlet where a large particle in the suspension initiates the clog in a stochastic manner. Without the smaller outlet constriction, however, flowrate decays linearly in a single straight microchannel where adhesive interactions exist between the particles and the constriction wall 15 .…”

Clog mitigation in a microfluidic array via pulsatile flows

“…Recently, Trofa et al numerically investigated clogging under both constant pressure and constant flow rate for adhesive particles. 48 They demonstrated the potential to predict numerically fouling and clogging for steady flows, given sufficient input physical parameters.…”