To jump or not to jump: Adhesion and viscous dissipation dictate the detachment of coalescing wall-attached bubbles
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| Main Authors: | , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866908617611935744 |
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| author | Demirkır, Çayan Yang, Rui Bashkatov, Aleksandr Sanjay, Vatsal Lohse, Detlef Krug, Dominik |
| author_facet | Demirkır, Çayan Yang, Rui Bashkatov, Aleksandr Sanjay, Vatsal Lohse, Detlef Krug, Dominik |
| contents | Bubble coalescence can promote bubble departure at much smaller sizes compared to buoyancy. This can critically enhance the efficiency of gas-evolving electrochemical processes, such as water electrolysis. In this study, we integrate high-speed imaging experiments and direct numerical simulations to dissect how and under which conditions bubble coalescence on surfaces leads to detachment. Our transparent electrode experiments provide new insights into contact line dynamics, demonstrating that the bubble neck generally does not contact the surface during coalescence. We reveal that whether coalescence leads to bubble departure or not is determined by the balance between surface energy, adhesion forces, and viscous dissipation. For the previously unexplored regime at low effective Ohnesorge number, a measure of viscosity that incorporates the effect of asymmetry between the coalescing bubbles, we identify a critical dimensionless adhesion energy threshold of $\approx$15% of the released surface energy, below which bubbles typically detach. We develop a global energy balance model that successfully predicts coalescence outcomes across diverse experimental conditions. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2501_05532 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | To jump or not to jump: Adhesion and viscous dissipation dictate the detachment of coalescing wall-attached bubbles Demirkır, Çayan Yang, Rui Bashkatov, Aleksandr Sanjay, Vatsal Lohse, Detlef Krug, Dominik Fluid Dynamics Chemical Physics Bubble coalescence can promote bubble departure at much smaller sizes compared to buoyancy. This can critically enhance the efficiency of gas-evolving electrochemical processes, such as water electrolysis. In this study, we integrate high-speed imaging experiments and direct numerical simulations to dissect how and under which conditions bubble coalescence on surfaces leads to detachment. Our transparent electrode experiments provide new insights into contact line dynamics, demonstrating that the bubble neck generally does not contact the surface during coalescence. We reveal that whether coalescence leads to bubble departure or not is determined by the balance between surface energy, adhesion forces, and viscous dissipation. For the previously unexplored regime at low effective Ohnesorge number, a measure of viscosity that incorporates the effect of asymmetry between the coalescing bubbles, we identify a critical dimensionless adhesion energy threshold of $\approx$15% of the released surface energy, below which bubbles typically detach. We develop a global energy balance model that successfully predicts coalescence outcomes across diverse experimental conditions. |
| title | To jump or not to jump: Adhesion and viscous dissipation dictate the detachment of coalescing wall-attached bubbles |
| topic | Fluid Dynamics Chemical Physics |
| url | https://arxiv.org/abs/2501.05532 |