Impeller rotation on free surface

[sridharsahoo366]

I have simulated a paddlewheel (impeller) at the water-air interface in the pond. I have used a multiphase Eulerian model (inhomogeneous), with water at the bottom (a H2O/O2(g) mixture) and air at the top (a N2/O2(g) mixture). The species transport model was kept on. The impeller was rotating at 80 rpm. The results showed perfect rotation of the paddlewheel, and the phase volume fraction showed that, water region is creating movement and turbulence in the interface. However, the oxygen from the water phase (phase 2) moved towards the top, and the oxygen from the air (phase 1) moved towards the bottom. This does not allign with the objective. I want to observe the increase in dissolved oxygen as the paddlewheel rotates, creating diffusion and splashing at the surface. Please suggest the changes that need to be made. 

Thanks in advance..

[Rob]

You've got oxygen gas in the liquid region? 

[sridharsahoo366]

Yes, but the way it should enter is mismatching with experimental data. 

[Rob]

You really have oxygen GAS in the liquid? I'd understand dissolved oxygen, which can be dropped out of solution to become oxygen gas.