why do we get the message "non-positive area exists" when we do grid check in fluent. I've created an uniform mesh of 1 cm spacing in a rectangular area of 0.2 by 1 m. what to do when this message comes? anyone please help me.

Did you use Gambit to create the mesh? Is this a 2D or 3D case?

Yes i used GAMBIT for meshing. it is 2D case.

Ok, there is not a lot of info to go by here. Did you check the grid quality as well in Gambit?

The "non-positive area" can occur during meshing when the meshing scheme ends up causing cell boundaries to cross. I have seen this happen in highly curved surfaces when using a boundary layer. But you seem to have a very simple case.

Is this an axisymmetrical domain?