Direct numerical simulation of bubbly flow in the turbulent boundary layer of a horizontal parallel plate electrochemical reactor

We perform direct numerical simulation (DNS) of a turbulent bubble-laden channel flow of shear Reynolds number Reτ = 131 to analyse mass transfer in a parallel plate electrochemical reactor. We set aside the electrochemical part of the problem and focus on the simulation of a turbulent channel flow of a liquid electrolyte with gas bubbles evolving from an electrode located at the bottom wall of the channel. We use an Eulerian–Lagrangian representation to simulate dispersed two-phase flow, where two-way momentum coupling between the bubbles and the electrolyte is taken into account. Three-dimensional simulations are obtained using a distributed memory parallel computer architecture. Investigations on the bubble motion due to advection and gravitational rise are carried out and the interaction of bubbles with turbulent flow structures is analysed. Furthermore, the role of the lift force acting on the bubbles is investigated. Mean volume fraction statistics are shown for validation purposes. An analysis of instantaneous flow fields and bubble distributions as well as order-of-magnitude analyses are used to determine which forces are mostly influencing the bubble dynamics and dispersion.