Flow of simple liquids down narrowssVgrooves

The dynamics of spreading of simple liquids down straight, narrow ssV grooves open at the top were captured by real-time video imaging. Groove depths in polished copper ranged between 40 and 100 \ensuremath{\mu}m and extended approximately 2 cm with ssV angles of 30\ifmmode^\circ\else\textdegree\fi{}, 60\ifmmode^\circ\else\textdegree\fi{}, and 90\ifmmode^\circ\else\textdegree\fi{}. The surface tension to viscosity ratios ranged from 46 to 970 cm/sec and the capillary number was small, Ca\ensuremath{\ll}1 in all cases. The length of the spreading liquid scaled with \ensuremath{\surd}t accurately for every case examined; the dynamics were well represented by two numbers, the location of the front in reduced coordinates and a diffusion coefficient. A simple theory is presented for the dynamics of the advancing front that requires no adjustable parameters and fits well the experimental data collected with six alcohols. Unlike drop spreading, the ad hoc slip boundary condition of that theory is not invoked for the open groove problem; only the static advancing contact angle is used.