Assessment of a subgrid-scale model for convection-dominated mass
transfer for initial transient rise of a bubble
Abstract
The mass transfer between a rising bubble and the surrounding liquid is
mainly determined by an extremely thin layer of dissolved gas forming at
the liquid side of the gas-liquid interface. Resolving this
concentration boundary layer in numerical simulations is computationally
expensive. Subgrid-scale models mitigate the resolution requirements
enormously and allow approximating the mass transfer in industrially
relevant flow conditions with high accuracy. However, the development
and validation of such models is difficult as only integral mass
transfer data for steady-state conditions are available. Therefore, it
is difficult to assess the validity of the sub-grid models in transient
conditions. In this contribution, we compare the local and global mass
transfer of an improved subgrid-scale model for rising bubbles (Re =
72-569 and Sc = 10^2-10^4) to a single-phase simulation approach,
which maps the two-phase flow field to a highly-resolved mesh comprising
only the liquid phase.