Forced flows in liquid bridges

Wetting of solid surfaces by liquid deposition, contact dispensing, drop transfer, collision of wet particles, or during coating processes is often accompanied by the formation of liquid bridges between two or more solid substrates. They appear in many applications, like material science, microfluidics, biomedical, chemical, or aerospace engineering, and different fields of physics. In this study, the flows accompanying lifting of a Hele-Shaw cell, stretching or shearing of a liquid bridge, as well as liquid bridge flows observed during printing processes and other important applications, are briefly reviewed. Such flows are governed by surface tension, inertia, stresses associated with the liquid rheology, and forces caused by the substrate's wettability. Instabilities of liquid bridges lead to the formation of finger-like structures on the substrate or the appearance of cavities at the wetted region of the wall. The time required for jet pinch-off also determines the residual liquid volume on both solid bodies.