A small presentation of ICEM

ICEM is very powerful and therefore a big program that is difficult to master in only a few hours. We briefly describe here the three main steps to follow to obtain a mesh by giving a picture associated with each step.

• Step 1 DDN:

In ICEM>Geometry

It is a CAD tool that is used to build the geometry. The mesh is not really important at this time. Yet with a little practice it seems imortant to think ahead and to build the geometry using curves and surfaces that will be easy to manipulate when it will the time to do the projections needed for the mesh.

On this image the 3D pipe junction is complete. The surfaces are B-splines, so they can be used by ICEM later. It is important to convert all the needed surfaces into B-splines and to delete the rest to avoid problem in the meshing.

• Step 2 DDN tetin:

In ICEM>Geometry

In tetin we are again in the DDN environment and we define the families and the domain. The families regroups all the surfaces or curves that can be considered as being of the same nature. For exemple in the 3 pipe junction we have the family cyl1 and cyl2 that are two families to the half cylinder surfaces. These families will later be defined as wall before exporting the mesh. The domain must be created in order to indicate to the mesher which region is the interior zone.

• Step 3 the meshing:

In ICEM>Meshing

There are several way to mesh depending on the kind of elements that you want to use. The two main types are tetra and hexa. Within tetra there is more option like using for exemple an O-grid that can be especially helpful with round shapes. To mesh hexa, ICEM divides regtangular shapes and the projects the elements into the physical shape. To have a good mesh it is therefore a good idea to ease this process by blocking the geometry. The created blocks are th reference for the meshing. Indicating the  projection will avoid bas cells to appear. This part is the main work of the meshing.

On this picture, the 3D pipe junction has been blocked. In green we have defined the projection of the block on the geometry, that will be used for creating the real mesh after deforming the blocks.

• Step 4 exporting the mesh:

On this image we can this a completed tetra mesh. The next thing to do is to chose a solver and to create the files that will be used by the computation program like Fluent.

For STAR-CD, choose STAR-CD as solver and proceed as for FLuent: set the boundaries and create the STAR-CD files (Input Star-CD). A .inp file is created in the transfer directory.

Then start Prostar. Go to Create or Import Grid>Import Grid. Select the ICEM option and select the correct file. Click on Import grid.

The process should be finish at this time. It is best to check the boundaries in Define boundaries and the Thermophysical model.