Mesh

You should have completed the Laminar Pipe Flow tutorial before continuing with this one. The starting point for this tutorial is the ending point of the one before it. If you bring up the project we have already completed, you can follow the next steps.

Right click on Mesh . Then click on Duplicate, which will duplicate the mesh from the previous tutorial. Enter "Turbulent Flow" in the highlighted field to rename it. At this point your project schematic window should appear as below:

Image Added

Next, double click on the Mesh cell so we can edit the mesh.

We need to change the edge sizing, as we did in the previous tutorial, to 100 by 30 (instead of 100 by 5).  We are also going to need to bias it.  This is because we want smaller divisions the closer you get to the wall. First, right click on Edge Sizing 2 in the Project tree on the left, and click Delete to remove the existing edge sizing on the inlet and outlet.

Next, we'll apply an edge sizing with bias to the inlet, the left end of the pipe. Click Mesh Control > Sizing. Using the edge selection tool, highlight the inlet (left end) of the pipe and click Apply next to Geometry. As in the Laminar Pipe Flow tutorial, change Type to Number of Divisions, and enter 30. Change Behavior to Hard. Now, let's apply a bias to the edge sizing. Under Bias Type, select the second option, - – — ----. Enter a Bias Factor of 10. Your Details of "Edge Sizing 2" should now appear like the image below.

Image Added

Now we would like to apply an edge sizing to the outlet, the right end of the pipe. Once again, we'll use 30 divisions, with a bias factor of 10 and with the smaller divisions at the top, near the wall. This time, when selecting Bias Type, choose the first option, ---- — – -. This will put the smallest divisions at the top. Other than this, the procedure is the same as for the inlet. When complete, your Details of "Edge Sizing 3" should look like this:

Image Added

Right click on Mesh and select "Generate Mesh". The bias factor generates a finer mesh near the pipe wall. This is done to compute the small fluctuation in fluid property near the wall.

Image Added

Next, close the meshing window to return to the main project view.

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

...

Recall that we created the following boundary types for the 100x5 mesh in the Laminar Pipe Flow tutorial:

These boundary types are still retained even if the edges are remeshed since the edges themselves were not deleted. To verify this:

Operation Toolpad > Zones Command Button > Specify Boundary Types

Check that the following is in the Name/Type list:

Additionally, click on show labels. You should now be able to see each of the boundary names on the respective edges in the Graphics Window. Verify that the boundary types specification is correct.

Save and Export

As in the previous tutorial, we will now save and export the mesh.

Main Menu > File > Save

Main Menu > File > Export > Mesh...

Type in pipe100x30.msh for the File Name:. Select Export 2d Mesh since this is a two-dimensional mesh. Click Accept.

Check that pipe100x30.msh has been created in your working directory.

Exit GAMBIT: Main Menu > File > Exit and save the session.

Go to Step 4: Physics Setup

Go to all FLUENT Learning ModulesGo to Step 4: Set Up Problem in Fluent