Direct Numerical Simulation of Single Gaseous Bubbles in Viscous Liquids

The rise behavior of single air bubbles of different size in viscous liquids (water/glycerol mixtures) is investigated using a 3D Direct Numerical Simulation method. The simulations where performed by the ITLR inhouse code Free Surface 3D (FS3D) which solves the incompressible Navier-Stokes equations using a Volume-of-Fluid (VOF) technique. The computational effort is reduced by using a moving frame of reference. This moving frame allows the simulation of a large scale rising trajectory. The numerical results, which comprise the terminal rise velocity, the aspect ratio of the deformed bubbles and the resulting bubble shape are compared to experimental data from literature. The simulations were performed on the NEC SX-8 and NEC SX-9 platforms of the HLRS.