  This study explores the dynamics of dispersed bubbly turbulent flow in a
channel using interface-resolved direct numerical simulation (DNS) with an
efficient Coupled Level-Set Volume-of-Fluid (CLSVOF) solver. The influence of
number of bubbles (96 and 192), flow direction, and Eotvos number was examined
across eight distinct cases. The results indicate that in upward flows, bubbles
tend to accumulate near the wall, with smaller Eotvos numbers bringing them
closer to the wall and enhancing energy dissipation through increased
turbulence and vorticity. This proximity causes the liquid phase velocity to
attenuate, and the bubbles, being more spherical, induce more isotropic
turbulence. Conversely, in downward flows, bubbles cluster in the middle of the
channel and induce additional pseudo-turbulence in the channel center, which
induce additional turbulent kinetic energy in the channel center. The study
further examines budget of Turbulent Kinetic Energy (TKE) and the exact balance
equation for the Reynolds stresses, revealing that near-wall bubble motion
generates substantial velocity gradients, particularly in the wall-normal
direction, significantly impacting the turbulence structure.
