rising bubble vof simulation in fluent
 

Hi
I want to do the rising bubble simulation using vof model of fluent.The system is an air bubble in a stagnant liquid towards the bottom of narrow column.I created the geometry containing three walls and a pressure outlet and did the meshing by using quadrilateral mesh because its a two dimensional problem. The problem is when the mesh is imported to fluent and read,there are some additional walls created and i am not getting the result which I should get. If anyone has done or knows about this problem please tell me the solution.

Regards

Vinita