FLUENT - Flat Plate Boundary Layer Step 6

Step 6: Verification & Validation

Plot Velocity Vectors

Let's plot the velocity vectors obtained from the FLUENT solution.

Results > Graphics and Animations > Graphics > Vectors

Zoom in a little using the middle mouse button to peer more closely at the velocity vectors.

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Remember to save the image using

Main Menu > File > Save picture

You can then select coloring, resolution and format for your picture. Then click on Save and give a name to the file to save it.

Plot Pressure Coefficients

Now we will display the pressure coefficient contour but first we need to set the reference values for velocity. Go back to:

Problem Setup > Reference Values

And select inlet under Compute From. Then go back to:

Results > Graphics and Animations > Graphics > Contours

Select Pressure...under Contours Of. Then select Pressure Coefficient from the second drop-down menu. Also, check the Filled checkbox and set Levels to 90. Then click on Display to update the display window.

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Zoom in at the leading edge. \

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Why is the pressure not constant at the leading edge of the plate?

Plot Skin Friction Coefficients

Now we will plot the skin friction coefficient along the flat plate.

Results > Plots > XY Plot

Change Pressure to Wall Fluxes. Then, change Wall Shear Stress to Skin Friction Coefficient. Under Surfaces, select plate. 
 
Click Plot.
 

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Now, compare your solution to the with the Blasius solution's skin friction by loading the file and then plotting it with your solution. (Download file here)

Also, you can change the symbol into lines by going to Curves... and click on the corresponding pattern that you like. Increase the Weight to 3 for readability. Both results should be fairly similar.

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Now we will look at the velocity along the plate at outlet.

Results > Plots > XY Plot

Uncheck Position on X Axis and check Position on Y Axis under Options. Under Plot Direction, set X to 0 and Y to 1. Under X Axis Function, select Velocity...Then, change Velocity Magnitude to X Velocity. Finally under surface, select outlet. Before we are ready to plot, click on the Axes... button and rescale the y-axis from 0 to 0.12. Also, check the Major Rules and Minor Rules for both axes. Remember that you must click the Apply button when performing changes in each axis.

Click Plot.

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To compare with the Blasius solution, download the solution here. Click Load File...and select the file you just downloaded. Then plot the solutions again to display both lines on the same graph.

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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.

Plot Line Rakes

Again, in the XY Plot window under New Surface > Line/Rake

Check the line tool checkbox under Options and set the initial coordinate to (0.5,0) and final coordinate to (0.5,0.5). Under the New Surface Name field, type in x_0.5 and then click the Create button to create the line.

We can now plot and compare the velocity profile at the mid point and the outlet of the flow.

Under Surfaces, select outlet and {}x_0.5 and Plot.

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Go to Step 7: Refine Mesh