Four-way coupled Eulerian–Lagrangian Direct Numerical Simulations in a vertical laminar channel flow

•Bubbles dynamics and their interactions with the walls and the liquid are fully resolved through a four-way coupling strategy.•Simulations involve a very large amount of bubbles.•DNS strategy gives access to a fine evaluation of the flow in the wall vicinity that is inaccessible in mixture models.•The mesh sensitivity has been investigated for cell sizes ranging between 0.7 and 12 bubble radii.•No strong differences have been observed between the purely elastic and the non-elastic rebound cases. Direct Numerical Simulations of a laminar two-phase flow into a vertical channel are investigated. An Eulerian–Lagrangian approach allows tracking each bubble position with a four-way coupling strategy, i.e. taking into account bubble-fluid and bubble-bubble interactions. The flow configuration has been chosen to highlight the buoyancy effects due to significant values of void fraction (high numbers of bubbles); hence the bubbles collisions and wall effects are the critical parameters to ensure the dispersion of the bubble plume. The DNS approach is self-consistent and does not rely on closure relations or empirical correlations for describing the collective bubble dynamics. It is found that the DNS predicts well the behavior of the bubble plume and its back effect on the liquid phase when compared with a mixture model and experimental data. The elastic nature of collisions, the sensitivity of the mean and RMS values of velocities and void fraction to the mesh quality are explored.