Taylor bubble flow in microchannel having an obstacle

Abstract

A two-dimensional numerical study of Taylor bubble flow in a microchannel (diameter 0.2 mm) having an obstacle is carried out. A square shaped obstacle, of side 0.02 mm is placed inside the microchannel. Taylor bubble flow is created using T-junction. Water and air enters through two inlets and form Taylor bubble at the T-junction. The obstacle is placed at an appropriate distance from the T-junction, where the water and gas fluids are getting mixed, along the downstream such that the stabilized Taylor bubble will touch the obstacle. This shows that the obstacle will be touched by the Taylor bubble which is already in steady motion. The obstacle position is varied along the perpendicular to the direction of fluid flow. Initially the obstacle is kept at the center of the microchannel i.e., it provides an equal space of 0.9 mm on either of its sides inside the microchannel. As the Taylor bubble touches the obstacle it splits into two parts and moves through both sides of the obstacle with a perfect symmetric flow. The bubble joins again and gets to its original form as it passes through the obstacle. Then the obstacle is moved 0.02 mm away from the center towards one side, i.e., it provides a gap of 0.11 mm and 0.07mm on either side of the obstacle respectively. In this case as the Taylor bubble touches the obstacle it doesn’t split into two parts rather the whole bubble tries to move to the upper side of the obstacle i.e. maximum area side. Similar phenomenon is observed as the obstacle moves further away from the center line towards one side. The liquid-gas interface is continuously changing its shape due to the disturbance caused by the presence of the obstacle. This creates turbulence inside the liquid plugs present in between the two consecutive bubbles, which is shown by using the velocity vector fields. This may raise hope to enhance more heat and mass transfer in the microchannels by placing multiple obstacles inside the microchannels