DNS of bubble columns

In this project, the hydrodynamics of the bubbly flow in a bubbly column is studied by mean of Direct Numerical Simulation (DNS). The main goal of this project is to derive generalized closure models for the hydrodynamical forces (i.e. lift and drag) acting on bubbles under various conditions. The second goal is to gain better understanding of the fluid dynamics in the bubble column system based on the detailed DNS simulations.

These goals will be accomplished by three main modules:
• DNS simulation using HPC: The DNS of a full-scale bubble column is laborious due to high demanding of computational resources and time. In order to reduce the cost, we adopt an advanced DNS code with a so called adaptive grid-refinement technique. This helps to cut down the number of grid cells remarkably without any sacrifice of the numerical resolution. Moreover, we have been granted with tremendous computational resources by SURFsara computing center, which enables us to carry out such large-scale DNS simulations.
• Data analysis: During the simulation, relevant data will be extracted and logged. These raw data are huge in size, which needs careful examination and post-processing. Different methods will be used to calculate the interfacial forces on each bubble. Then we will use the numerically “measured” forces to formulize the corresponding models.
• Theoretical interpretation: The DNS results enable us to look into different aspects of a bubble column system. It’s possible for us to discover the unknown physics involved in the bubble column system by combining the observation of flow field and the quantitative analysis of bubble dynamics.

People involved in this project: Xiaowei Zhu, Yali Tang, Niels Deen