Abstract
The thermocapillary flow induced by a gas bubble in a Newtonian liquid layer subjected to a stable temperature stratification is investigated. This flow is analyzed for a special configuration when the surface tension and buoyant forces oppose one another. The driving mechanism is the surface tension gradient related to the Marangoni number whereas the stabilizing effects are the viscous and buoyant forces related to the Prandtl and the Rayleigh numbers. In a previous work, this flow has been investigated experimentally for a few combinations of these three parameters. In order to make a more systematic study of the influence of these parameters, numerical simulations are used as a decisive tool. Indeed, it allows the contribution of the different mechanisms to be evaluated. To validate the finite element model, developed for this purpose, the numerical results are first compared to experimental ones. Then, the influence of these three dimensionless parameters on the flow pattern and the magnitude of the flow is analyzed. This sensitivity study is supplemented by a convergence study. It appears that the Rayleigh number modifies the flow pattern but has little influence on the strength of the primary vortex induced by the bubble. On the other hand, the Marangoni and Prandtl numbers induce little change in the flow pattern but they respectively enhance and reduce the strength of the primary vortex. This systematic analysis leads us to propose an empirical relationship for the strength of the flow.
Published Version
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