Unravelling bubble-induced turbulence

• Applicants: Dr.-Ing. Hendrik Hessenkemper; Dr.-Ing. Tian Ma
• Subject Area: Fluid Mechanics
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 536223645

When small bubbles are introduced into a turbulent flow, we know from daily experience that the bubbles will be swept up by the swirling eddies and vortices of the flow. But how is the behaviour of finite-sized bubbles in turbulence, and how does this impact whether the bubbles smooth out intensify fluctuations in the turbulent flow that is transporting them? These questions are not only of industrial and technological significance, but are also of profound importance for a fundamental understanding of the physics of multi-phase turbulent flows. The present proposal will deliver answers to these problems by using a powerful mixture of theory and experiments. Recently, we have demonstrated that bubbles strongly affect turbulence across all scales from the largest scales determined by the flow geometry to the smallest dissipative scales. Our recent research has elucidated ways in which bubbles generate strong anisotropy of the flow with surprising dependencies on the bubble properties, and the way they enhance “extreme events” in the turbulence. These discoveries point toward exciting new insights into multiphase turbulence and implications for bubble motion in turbulent flows, which will be explored in this project. In the present proposal, (A) 3-dimensional velocity measurement techniques will be applied to generate an open-access turbulence database with different bubble-laden flow configurations. This will provide the foundation for dissecting (B) the multi-scale properties of the bubble-induced turbulence and (C) developing accurate turbulence models for industrial-scale simulations of these flows. The present proposal will boost our fundamental understanding of turbulence in bubble-laden flows and provide new modelling approaches for a wide range of fields such as process engineering, ocean sciences and renewable energy.

• DFG Programme: Research Grants