Modelling of double bubbles coalescence behavior on different wettability walls using LBM method

In this paper, the lattice Botlzmann method is used to simulate the coalescence behavior of double bubbles on different wettability walls. For hydrophilic surfaces, the supplementary microlayer can be captured when bubbles coalesce, and there is an obvious heat flux peak. For the hydrophobic surface, there is no supplementary microlayer because the bubbles coalesce at the bottom. It is difficult to move the three-phase contact line during coalescence, and the heat flux is slightly improved. The separation distance of the bubbles has a certain effect on the heat transfer of the wall. There is a critical separation distance (the maximum average heat flux distance), and as the contact angle increases, the critical separation distance of the bubble also increases. Comparing the bubble coalescence process on hydrophilic and hydrophobic surfaces, the average heat flux of a hydrophobic surface is lower than that of a hydrophilic surface and the bubbles on the hydrophobic surface are more likely to coalesce on the wall to form a vapor layer, which may cause damage to heat transfer or trigger the critical heat flux. •Heat flux variations during the horizontal coalescence of double bubbles are simulated.•There is a maximum average heat flux separation distance when bubbles coalesce.•For hydrophilic surfaces, there is a supplementary microlayer and an obvious heat flux peak when coalescing.•Compared with hydrophilic surfaces, bubbles are more likely to coalesce on hydrophobic surfaces.