Problem using StarCD for the mesh
A first mesh was made by using StarCD. The way  to do this is the following :
Open the Star Guide
Click on Create and Import Grids
Click on Create Grids
Choose Create 3-D Grids
Then, choose the coordinate system, in our case cylindrical (2), and the type of the cells, which is fluid for this case. Finally, define the domain you want to use.

All these steps are summarized with the photo below :

Hereunder is the result obtained. The problem is that StarCD defines a boundary which is not wanted. Thus, once the calculation is done, we can see that this boundary acts as a wall. This is not really interesting in our case. That is why we preferred to use Gambit to create the mesh.