ICEM Walkthrough – From Nothing to Fluent

Here are instructions which should walk you through the process of creating the test inlet grid already provided to you in ICEM. This document will cover the entire process, from geometry to export. During certain steps, it may refer you to tutorials you have previously completed for the mechanics of completing certain tasks.

Step 1. Input the geometry points.From the Geometry tab, open the Create Points pane. Deselect the Inherit Part option and type

“POINTS” in the Part field. Select the Explicit Coordinates button and add the following points: (0,0), (3.493,0.491), (6.986,0), (3.493,-0.491), (-10,30), (10,30), (10,-30), (-10,-30), (-10,-4), (-10,0), (-10,4), (10,4.2), (3.005,4), (10,4), (10,0), (10, -4), (3.005,-4), (10,-4.2). Right click on POINTS in the Parts menu and select Info, then confirm from the text output in the lower right that exactly 18 points are in this part family.

Step 2: Make the boundaries.Open the Create Curve pane and select the From Points button. Type “FREE” in the Part field.

Create the boundary curves that will eventually have the freestream (pressure-far-field) boundary condition. Use only two points per curve. Then type “OUT” in the Part field and create the outlet boundary curves, and then type “WALL” in the Part field and create the wall boundary curves.

Step 3: Create the initial block.As shown in the ICEM tutorial, create the initial 2D Planar block in the LIVE part. If ICEM

throws an error and creates an infinitely long block around your geometry, you must save your project and restart ICEM at this point. (This seems to be a math error of some kind, probably divide-by-zero.) As shown in the ICEM tutorial, divide the initial block into a 7x4 grid.

Step 4: Delete the solid object blocks.As shown in the ICEM tutorial, delete the following blocks, indexed from the top left corner:

Row 2, Column 3; Row 2, Column 4; Row 4, Column 2, Row 4, Column 3; Row 6, Column 3; Row 6, Column 4. These areas will be mapped to the solid areas of the domain.

Step 5: Join unneeded vertices.Under the Blocking tab, open the third pane, Merge

Vertices. If it does not appear automatically, select the first button, Merge Vertices by Number. We are going to merge the vertices of blocks upstream and downstream of the deleted solid object blocks in order to create sharp points. The numbers of the vertices will vary depending on the order in which you split the blocks, but the result should look like the picture provided; the black-outline deleted areas should come to a point at their upstream ends (the centerbody should also come to a point at its downstream end) and a single line should extend from each of those points to the edge of the domain.

Step 6: Associate and move the blocking’s vertices and edges.As shown in the ICEM tutorial, for block vertices that have a logical point to associate with,

associate those vertices with those points. This will move those vertices into place. As shown in the ICEM tutorial, associate the block edges with the appropriate curves. Note that you should have four edges and four curves on both the upstream and downstream ends of the domain, and you should make one-to-one associations for each of them, rather than associating them as a group. However, each cowling wall segment in the geometry will have two block edges to associate with, and those can be associated as a group, and the top and bottom of the domain will each have four block edges and a single geometry curve, which can also be done as a group. Finally, as shown in the ICEM tutorial, manually reposition any remaining vertices to maximize cell orthogonality.

Step 7: Mesh the grid.As shown in the ICEM tutorial, set the Curve Mesh Parameters for all curves (use the All

Visible glasses icon when picking) to a Maximum Size of 0.5. Click Apply, then enable the Pre-Mesh under Blocking in the Model tree, affirm the recalculation of the pre-mesh, and visually examine the results. Under normal circumstances, you would then repeat this step in more detail to refine your grid to your needs.

Step 8: Generate the mesh.As shown in the ICEM tutorial, right-click on Pre-Mesh under Blocking in the Model tree and

select Convert to Unstruct Mesh. Save your project to save the mesh as projectname.uns. In the Model tree, make the following selections: disable Geometry; enable Lines and disable Shells under Mesh, disable Vertices under Blocking, and disable POINTS and LIVE under Parts. Confirm from the colors of the display that the appropriate edges of the mesh are assigned to the proper part families. If the colors of two part families are too similar, right-click on one of them in the Model tree and select Change Color.

Step 9: Set boundary conditions.As shown in the ICEM2Fluent walkthrough, select the Fluent V6 solver and make that the

default selection. Apply the appropriate boundary condition to each part family displayed under Edges in the Boundary Conditions window.

Step 10: Save the mesh and confirm export in Fluent.As shown in the ICEM2Fluent walkthrough, save your project, then save the Fluent input file.

Load the input file into Fluent and confirm that the boundary condition zones are appropriately divided. Save your Fluent case file.

These steps should result in a working, properly zoned Fluent grid. When refining a grid or making changes to a geometry, the changes should only impact one or two of these steps. Remember, when trying to create a grid for a different geometry, to think ahead and devise the simplest blocking schematic that will still allow you to control the orthogonality and skew of your grid cells.