Page History

...

Step 7: Verification & Validation

It is very important that you take the time to check the validity of your solution. This section leads you through some of the steps you can take to validate your solution.

Refine Mesh

Let's repeat the solution on a finer mesh with more smaller element size.Repeat the mesh steps, but this time use edge sizing of 50 and 0.02. In the workbench, under Force Convection project, right click on Fluid Flow (FLUENT) and click duplicate. Rename the duplicate project to Force Convection Refined Mesh. You should have two projects cell in workbench.
Image Added

Double click on Mesh for Forced Convection Refined Mesh. A new ANSYS Mesher window will open. Under Outline, expand mesh tree and click on Edge Sizing.
Image Added
 

Under Details of "Edge Sizing", enter 50 for Number of Divisions.
Image Added
Similarly, specify element size of 0.02m for Edge Sizing 2. 
Image Added
 

Click Update Image Added to generate the new mesh. Under Statistics, we should have mesh with 15,300 elements.
Image Added

Close the ANSYS Mesher and go back to Workbench windows. Under Forced Convection Refined Mesh, right click on Fluid Flow (FLUENT) and click Update. Wait for a few minutes for FLUENT to obtain a solution.

We would want to compare the solution between the two meshes. To do that, drag the Solution cell of Forced Convection Refined Mesh to Results cell of Forced Convection.
Image Added
 

Finally, double click on Results cell of Forced Convection to compare. In the Outline tab, click on the results of interest to analyze.

Centerline Pressure

Let's us look first look at the Pressure drop along the centerline.
Image Added

https://confluence.cornell.edu/download/attachments/111221577/Centerline%20Pressure%20Compare.png

The refined mesh pressure correspond better with the experimental data. 
 

Centerline Temperature

Image Added

https://confluence.cornell.edu/download/attachments/111221577/Centerline%20Temperature%20Compare.png

Wall Temperature

Image Added

https://confluence.cornell.edu/download/attachments/111221577/Centerline%20Pressure%20Compare.png

 
 

The difference in maximum stress at the cut out area is less than 0.3%.

This means that our mesh is refine enough and the solution obtained using the original mesh is probably good enough.

Do keep in mind that one would have to make more detailed comparisons between the solutions on the two meshes before we can make a definitive statement about the mesh independence of our results.