Gas bubbles in simulation and experiment

An experimental setup for the examination of single bubbles, rising in a liquid, is presented. Its main part is a rotating chamber, in which the bubble is spatially stabilized by a balance of buoyancy, drag, and lift forces. This allows for long observation periods in time. Experimental results are presented for air bubbles in silicone oil. The experimental results are validated by a comparison with numerical simulations. A modified, mass-conserving level-set method is used for the representation of the free interface, while an immersed-boundary formulation is engaged for the conservation equations. The agreement between experiment and simulation, and to available correlations from literature, is found to be perfect. It is shown that the influence of the liquid shear due to the rotation is negligible. Also, for the presented liquid system, no influence by Marangoni stresses could be found, which makes the system of air and silicone oil a good choice for validation purposes.

Bubbles in rotating-chamber experiment are spatially fixed. They can be subject to all kinds of long-term investigations.Figure optionsDownload high-quality image (57 K)Download as PowerPoint slideResearch highlights
► Rotating-chamber experiment is a valuable instrument for long-term investigations of rising bubbles in liquids.
► Simulations based on the immersed-boundary formulation and a mass-conserving level-set method validate this feature in all details.
► With spatially-fixed bubble a great variety of measurements appears possible over long periods in time.