Laminar Pipe Flow

Problem Specification
1. Create Geometry in GAMBIT
2. Mesh Geometry in GAMBIT
3. Specify Boundary Types in GAMBIT
4. Set Up Problem in FLUENT
5. Solve!
6. Analyze Results
7. Refine Mesh
Problem 1
Problem 2

Step 3: Specify Boundary Types in GAMBIT

Create Boundary Types

We'll next set the boundary types in GAMBIT. The left edge is the inlet of the pipe, the right edge the outlet, the top edge the wall, and the bottom edge the axis.

Operation Toolpad > Zones Command Button > Specify Boundary Types Command Button

This will bring up the Specify Boundary Types window on the Operation Panel. We will first specify that the left edge is the inlet. Under Entity:, pick Edges so that GAMBIT knows we want to pick an edge (face is default).

Now select the left edge by Shift-clicking on it. The selected edge should appear in the yellow box next to the Edges box you just worked with as well as the Label/Type list right under the Edges box.

Next to Name:, enter inlet.

For Type:, select VELOCITY_INLET. (Note: Sometimes all the items in a dropdown menu will not be visible. If you cannot find the VELOCITY_INLET option in the Type menu, try maximizing the window. If it is still not visible, try auto-hiding your taskbar. Right-click on the taskbar and go to properties.)

Click Apply. You should see the new entry appear under Name/Type box near the top of the window.

Repeat this process for the other three edges according to the following table:

Edge Position	Name	Type
Left	inlet	VELOCITY_INLET
Right	outlet	PRESSURE_OUTLET
Top	wall	WALL
Bottom	centerline	AXIS

You should have the following edges in the Name/Type list when finished:

Save and Export

Main Menu > File > Save

Main Menu > File > Export > Mesh...

Type in pipe.msh for the File Name:. Select Export 2d Mesh since this is a 2 dimensional mesh. Click Accept.

Check pipe.msh has been created in your working directory (the box will be filled in red).

Go to Step 4: Set Up Problem in FLUENT