Figure 2
From: Transition-state theory predicts clogging at the microscale

Brightfield microscopy images at t = 0 (a) and t = 3377 s (b) for a repulsive suspensions, in which flow direction, filter cake and a clog are indicated with arrows. Grey channels are perfused with the suspension; as a clog appears, the channel becomes white down-stream, as particle flow is blocked, while the channel turns dark upstream from the clog due to the accumulation of excess particles.