Passive Control of Capillary Rise Dynamics in Micro-Channels*

Capillary rise, a fundamental fluid-structure interaction, is influenced by channel geometries and fluid properties.  This study investigates the dynamics of capillary rise in micro-channels using numerical methods to develop passive control strategies. We implemented sinusoidal variations in the channel cross-section and investigated a wide range of contact angles, and demonstrated precise control over the fluid front's ascent rate. The benefits achieved over conventional capillaries have therefore influenced the design of architected capillaries. Scaling of the liquid height is performed to reveal the rate of liquid rise for multiple contact angles collapsing into a single curve. This demonstrates the presence of a new mixed regime of fluid flow which is different from purely inertia dominated (~t) and viscous dominated (~t²) regimes that which governs the rate of rise.