problems in Two Phase flow using twoPhaseEulerFoam with OpenFoam 1.6
 

Hi Everybody,
I am trying to solve a bubble column case using twoPhaseEulerFoam. I am using OpenFaom 1.6 version. I see that after a certain time my liquid level (free surface) is becoming unstable and the liquid level (free surface) reaches on the top. This case I have already simulated using OF1.5 and it gives quite good results and I am able to validate these results with published experimental results.
I have following queries regarding this issue:
1) If someone solving Two Phase flow using OF 1.6 has faced the same problem?
2) Is there any trick to overcome this issue in OF 1.6?
3) Is there any listed bug in twoPhaseEulerFoam in OF 1.6?

Thanks in advance.
Raghu