 |
Flat Plate Boundary Layer |
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. Verify Results
Step 6: Analyze Results
Plot Velocity Vectors
Let's plot the velocity vectors obtained from the FLUENT solution.
Display > Vectors
Zoom in a little using the middle mouse button to peer more closely at the velocity vectors.
(Click picture for larger image)
Remember to save the image using
Main Menu > File > Hardcopy
Now we will display the pressure coefficient contour. First set the reference velocity.
Select inlet under Compute From
Display > Contours...
Select Pressure... and Static Pressure from under Contours Of. Then select Pressure Coeffient. Check Filled box and set Levels to 90.
(Click picture for larger image)
Zoom in at the leading edge.
(Click picture for larger image)
Why is the pressure not constant at the leading edge of the plate?
Now we will plot the skin friction coefficient along the flat plate.
Plot > XY Plot
Change Pressure to Wall Fluxes. After that change Wall Shear Stress to Skin Friction Coefficient. Under Surfaces, select plate. Click Plot.
(Click picture for larger image)
Compare with skin friction with the Blasius solution. Load the file and plot. (Download file here)
Also, you can change the symbol into lines by going to Curves... and click on the curresponding pattern that you like. Increase the Weight to 3 for readability. Both results should be fairly similar.
(Click picture for larger image)
Now we will look at the velocity along the plate at outlet.
Plot > XY Plot
Unchecked Position on X Axis and check Position on Y Axis. Under Plot Direction, set X to 0 and Y to 1. Under X Axis Function, select Velocity... After that change Velocity Magnitude to X Velocity. Finally under surface, click outlet. Before we are ready to plot, click on the Axes... and rescale y axis from 0 to 0.12. Also, checked the Major Rules and Minor Rules for x and y.
Click Apply and Plot.
(Click picture for larger image)
To compare with the Blasius solution, click Load File... and select the correct file (download file here)
(Click picture for larger image)
What is the noticeably different between two solutions? Why is the velocity overshoot 1 for FLUENT's solution?
Now we will compare the velocity profile at two sections. Create another section in the middle of the plate.
Surface > Line/Rake
Check the line tools box and set the initial coordinate of (0.5,0) to final coordinate of (0.5,0.5). Under New Surface Name, type in x_0.5.
We can now plot can compare the velocity profile at the mid point and the outlet of the flow.
Plot > XY Plot
Under Surfaces, select outlet and x_0.5 and Plot.
(Click picture for larger image)
Go to Step 7: Verify Results