Numerical investigation of water draining and oil-water draining from a square tank-A comparison

Abstract

The present study investigates the interfacial dynamics in case water and oil-water drain through a storage tank pipe. The tank has a square cross-section and is connected with a drain port at the bottom of the tank of diameter 0.009 m. Different eccentric positions are also considered. OpenFOAM software is used to analyze the liquid draining situation. A 3D numerical model is used to simulate the liquid draining situation. The VOF model is used to track the interface. Free surface in water draining is narrower than that in oil-water draining. At the extreme eccentric port of e0.96, the oil-water case leads to the formation of air bubbles from the vortex tip inside the tank. In the case of water draining, a zone of velocity de-acceleration was noticed at the central part of the drain pipe for e0. Velocity and pressure fluctuations are noted at the inlet of the drain port; however, reverse flow is not observed. Reverse flow in water draining was observed at e 0.96. The opposite is the trend for oil-water draining. A flow reversal is noted after the initiation of three-phase flow inside the drainpipe at e 0. However, since three-phase flow was initiated early in the tank for e 0.96, reverse flow is not noticed inside the drain pipe.