[hester]

Hello everyone,

I'm struggling with simulating a bubble column with twoPhaseEulerFoam in OF 2.3.0.

Air is injected into water, after Deen [1,2]. The dimensions are 0,15m x 0,15m x 0,45m. The simulation was done after Renze [3]. I didn’t include the liquid surface in my simulation. The continuous phase was modelled as turbulent using k-epsilon modell, the dispersed phase was modelled as laminar. But I didn’t get the wanted results. There is now oscillation of the bubble plume. The velocity for air is too big and the velocity of water is too small compared to the values from Deen (at height 0,25m). I think, it looks like there is a problem with the momentum transport between the phases. Drag, virtual mass and lift force were taken into account.

I also tried the mixtureKEpsilon modell, the description looks promising [4]. The results showed the expected bubble plume oscillation. But the results were worse, there’s strange behaviour at the top of my simulation regime (see attached pictures). Is it even possible to use this turbulence modell without including the liquid surface? Nevertheless, I think mixtureKEpsilon is the modell of choice here, I just haven't figured out how to make it work. Or would the standard k-epsilon modell suffice?

I included my case file (with kEpsilon modell). The setup with mixtureKEpsilon is the same. I hope someone could take a look and give me some advice as to where my error is. This is my first multiphase simulation and I've been struggling for a while now.

Thank your for your advice in advance!

hester

[1] N. G. Deen, T. Solberg, and B. H. Hjertager. Numerical simulation of the gas-liquid flow in a sqaure cross-sectioned bubble column. CHISA 14th international congress of chemical and process engineering, Praha, Czech Republic, 2000.
[2] N. G. Deen, T. Solberg, and B. H. Hjertager. Large eddy simulation of the gas-liquid flow in a square cross-sectioned bubble column. Chemical Engineering Science, 56:6341–6349, 2001.
[3] P. Renze, A. Buffo D.L. Marchisio, and M. Vanni. Simulation of coalesence, breakup, and mass transfer in polydisperse multiphase flows. Chemie Ingenieur Technik, 86:1088-1098, 2014.
[4] A. Behzadi, R.I. Issa, and H. Rusche. Modelling of dispersed bubble and droplet flow at high phase fractions. Chemical Engineering Science, 59:759-770, 2003.