Hi Rob.nThx for the quick reply. Since I am using the student version of Fluent, I think it would be better if I exclude the solid wall, so that I can put my limited nodes to better use.nFrom what I understood, in order for thin wall to work, the outer face for gas domain and the inner face for water domain need to be in contact with each other, without a gap/empty space in between, is that correct? Which means, after I remove the wall in geometry, I will need to pull one of the faces up to the other face as well. thus increasing the volume for either one of the domain, slightly.n