First, we tried to make the grid with StarCd but some difficulties appeared. Then, Gambit was used in order to perform the grid.

The grid with StarCd
There were any difficulties to make the grid. It was very quick if we use the following window.

We make Generate Mesh and we have got the grid :

With a zoom.

We remark that there is a double line across the section. When StarCd builds the grid between 0 and 360 degrees, the 360 section finishes with a wall. Consequently, we have a recirculation near this wall.

With a zoom.

        Finally, we decided to use Gambit in order to build the geometry and the grid.
 

The grid with Gambit
        The build of the grid with Gambit is very easy and quick. It is only a little bit difficult to make the importation to StarCd.
        You must to write first GAMBIT and then the command LP(case.neu).

        The geometry is the following one :
                - Rinterior = 0.6 m
                - Rexterior = 1 m
                - Height = 0.1 m

        The meshing is :
                - 18 meshes across a section
                - 180 meshes with theta
                - 2 meshes with the height

We obtain the following grid :

The 3 following graphs show the 3 boudary conditions.

        Interior wall with a constant velocity                                             Exterior wall without celocity