(316l) Open-Channel Capillary Flow in Minimal Support Structures

A stable liquid column with a large amount of free surface area is possible at low Bond number when stabilized by a support structure such as a wire helix or a polygonal array of parallel wires. In theory, stability persists for infinitesimal wire radii. Minimizing the solid in contact with liquid in a flow channel has advantages for drag reduction and for increased area for heat or mass transfer. Critical issues are the stable range of pressures which can be sustained in a continuous channel as well as the pressure at an advancing meniscus during initial penetration of liquid into the channel. Stable operating conditions for steady flow are identified in terms of structure geometry and contact angle. In the case of pulsatile flow the structure behaves essentially like an elastic tube with a very high compliance. The lateral motion of the free surface during pulsatile flow may have advantages for enhanced mixing. Capillary-driven flow in minimal support structures has potential applications in microfluidics and for fluid-fluid contacting in microgravity and in intensified processes.