[Mosayeb 92]

Hello all,
I want to make an inlet face on a cylinder at which the flow inters. It exits from the bottom of the cylinder. The geometry is shown in the attached picture.
Gambit doesn't accept this face on the cylinder and doesn't export it.
What should I do for this case?

all the best

[-mAx-]

I see blue entities, which means you only have surfaces.
As It is a 3d geometry you need a volume. (Volume appears in green).

[Mosayeb 92]

Thank you dear Maxime.

It is just a schematic of the geometry and I know it must be a volume.

I solved the problem, but there is another problem and I really appreciate it if you help me with that.
I want to model a cylinder in a wind tunnel to study both internal and external flow. When I import the mesh file in the fluent and solve the problem, the results are shown seprately for external and internal flow.
I mean the streamlines of the wind tunnel don't go through the cylinder and it seems there is no cylinder in the tunnel!
How should I model the geometry of the tunnel and cylinder together to have the flow inside and over the cylinder?

[-mAx-]

give a thickness of your cylinder.
The picture you posted, is only a cylinder as a split.
Either you give a thickness of your cylinder (and boolean operation for extracting just the fluid domain), or you enforce Gambit to treat your cylinder's surface as wall (in boundary conditions)