Computational Investigation of the Role of Eccentricity and Wall Wettability on Liquid Draining from a Storage Tank

Abstract

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.