A new criterion of coalescence-induced microbubble detachment in three-dimensional microfluidic channel

This work is motivated by an experiment of microbubble transport in a polymer microfluidic gas generation device where coalescence-induced detachment exhibits. We numerically study three-dimensional coalescence using the graphics processing unit accelerating free energy lattice Boltzmann method with cubic polynomial boundary conditions. The focus on (CIMD) microfluidics. From experimental observation, we identified that size inequality between two-parent bubbles and father (large) bubble are key factors to determine if CIMD will occur. First, analytical relationship equilibrium contact angle dimensionless wetting potential results without employed for verification validation, respectively. eighteen computational cases, derive new criterion CIMD: occurs when (nearly) equal relatively large radius. underlying mechanism behind this explored time evolution velocity vector field, vorticity kinetic entire coalescence. It found symmetric capillary force drives formation vertical flow stream horizontal alignment parent blockage downward due solid interface promotes intensity upward stream. Meanwhile, large-sized transfer amount from initial surface energy, which essential lead post-coalescence stage. Such expected impact design optimization microfluidics various applications.