Micro-convection mass transfer following bubble coalescence on a solid wall
Abstract
The Volume-of-Fluid implementation in the \href{basilisk.fr}{Basilisk} flow solver is employed to study mass transfer after coalescence-induced jump-off of bubbles on solid substrates at four combinations of bubble radius (Rm=150 and 25 μm, hydrogen-water properties) and Schmidt number (Sc=210 and 1). The results show a relatively strong downward entrainment of low-concentration liquid, induced by a rapid movement of the bubble interface at approximately 0.5 to 1 inertio-capillary time units after the moment of coalescence. At Sc=210, this leads to a highly local increase of the Sherwood number at a core region (roughly an area of radius Rm/2) below the south pole of the merged bubble, which persists long after the bubble departure due to the slow diffusion at large Sc. The enhancement factor of the Sherwood number is highly dependent on the state of the mass-transfer boundary layer at the moment of coalescence, increasing with smaller boundary layer thicknesses. Shortly after the jump-off, the velocity of the bubble is considerably damped and rapidly approaches its free-rise terminal velocity. The effect of micro-convection on the wall mass transfer coefficient at this stage is insignificant when isolated, similar to what is reported in the literature for purely buoyancy-driven bubble rise -- but slightly stronger.
Related
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BibTeX
@misc{saadat2026microconvection,
title = {{Micro-convection mass transfer following bubble coalescence on a solid wall}},
author = {Zahra Saadat and Michele Cattani and Amin Soltani and Pourya Forooghi},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.07232},
eprint = {2609.07232},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.07232},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Micro-convection mass transfer following bubble coalescence on a solid wall
AU - Zahra Saadat
AU - Michele Cattani
AU - Amin Soltani
AU - Pourya Forooghi
PY - 2026
DA - 2026/09/07
PB - arXiv
DO - 10.48550/arxiv.2609.07232
UR - https://arxiv.org/abs/2609.07232
AB - The Volume-of-Fluid implementation in the \href{basilisk.fr}{Basilisk} flow solver is employed to study mass transfer after coalescence-induced jump-off of bubbles on solid substrates at four combinations of bubble radius (R_m=150 and 25 μm, hydrogen-water properties) and Schmidt number (Sc=210 and 1). The results show a relatively strong downward entrainment of low-concentration liquid, induced by a rapid movement of the bubble interface at approximately 0.5 to 1 inertio-capillary time units after the moment of coalescence. At Sc=210, this leads to a highly local increase of the Sherwood number at a core region (roughly an area of radius R_m/2) below the south pole of the merged bubble, which persists long after the bubble departure due to the slow diffusion at large Sc. The enhancement factor of the Sherwood number is highly dependent on the state of the mass-transfer boundary layer at the moment of coalescence, increasing with smaller boundary layer thicknesses. Shortly after the jump-off, the velocity of the bubble is considerably damped and rapidly approaches its free-rise terminal velocity. The effect of micro-convection on the wall mass transfer coefficient at this stage is insignificant when isolated, similar to what is reported in the literature for purely buoyancy-driven bubble rise -- but slightly stronger.
ER -