The present work numerically examines the influence of
tank wall
wettability and drain port location on vortex formation and subsequent
bubble dynamics inside the drainpipe. A square cross-sectional tank
is used for this purpose. The dimension of the tank is typically smaller,
and such tanks are often used in the pharmaceutical and cosmetic industries
and patterning on solid surfaces. However, draining characteristics
might be different as, unlike larger-dimension storage tanks, the
surface force can play a significant role in this case. Three different
port positions and four different contact angles are used in this
study. Water is used as a draining liquid. The volume of fluid method
is used for tracking the interface between the two phases. The 3D
model is validated against experimental results. A hydrophobic wall
suppresses the formation of an air core vortex for the central port
location completely. Instead, a larger water drop is formed at the
top of the drainpipe inlet. This drop takes time to break into smaller
daughter drops and enter the drainpipe. Hence, the drain time increases
for the hydrophobic contact angle for the central port. Drain time
reduces significantly for eccentric locations with the hydrophobic
wall. A combination of contact angle and extreme eccentricity was
found to be effective for the quick draining of liquid from the smaller-dimension
square tank.