Flow Simulation in a 2D Bubble Column with the Euler-lagrange and Euler-euler Method

Bubbly flows, as present in bubble column reactors, can be simulated using a variety of simulation techniques. It is presented, how Computational Fluid Dynamics (CFD) methods are used to simulate a pseudo 2D bubble column using Euler-Lagrange (EL) and Euler-Euler (EE) techniques.

The presented EL method uses the open access software OpenFOAM to solve bubble dynamics with bubble interactions computed via Monte Carlo methods. The estimated bubble size distribution and the predicted hold-up are compared with experimental data and other simulative EE work with a reasonable consensus for both. Benchmarks with state of the art EE simulations shows that the EL approach shows good performance if the bubble number stays at a certain level, as the EL approach scales linearly with the number of bubbles simulated. Therefore, different computational meshes have been used to account for influence of the resolution quality.

The EL approach indicated faster solution for all realistic cases, only deliberate decrease of coalescence rates could push CPU time to the limits. Critical bubble number - when EE becomes superior to the EL approach - was estimated to be 40.000 in this particular case.