2D Heat Transfer Bubble Rising

Rising of a single bubble immersed in a fluid where the bottom part (red) is heated and has temperature higher then the upper part (blue). The bubble is then release and due to buoyancy effect, it crosses the heat transition line (green color). The heat transfer process takes place into the bubble dynamic and due to the bubble rising speed, the heat is advected along with the bubble, thus the two different temperature zones are consequently mixed. The 2D mesh can be seen on the left hand side figure and it comprises many triangles interconnected that need to be rearranged due to the high velocity gradient.