Flow transition in bubbly convection

We studied how neighbouring vapour bubbles interact during boiling and how this affects heat transfer and flow. Using two-dimensional simulations of water in a square enclosure heated from below and cooled from above, we varied the Jakob number ($Ja$), which compares sensible and latent heat, and the distance ($d$) between bubbles. When the bubbles are closer ($d$ less than half the enclosure height), the flow between them is stable and forms a dipole pattern. As $d$ increases, the flow becomes oscillatory and shifts to a tripole pattern. At higher $Ja$ (above ~2.8), strong instabilities appear, with bubbles detaching from the wall and forming a monopole pattern. At low $Ja$, heat transfer is driven mainly by phase change, while at high $Ja$, convection becomes dominant. Overall, heat transport is significantly enhanced in the presence of bubbles compared to standard thermal convection.