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h2. Step 6:

 Results


h4. {color:#cc0000}Plot Velocity Vectors{color}

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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[Higher Resolution Image|^step6_1.png]
{new window: Higher Resolution Image} ^step6_1.png{new window}

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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 {color:#990099}{*}{_}Save{_}{*}{color} and give a name to the file to save it.

h4. {color:#cc0000}Plot Pressure Coefficients{color}

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 {color:#990099}{*}{_}inlet{_}{*}{color} under {color:#990099}{*}{_}Compute From._{*}{color} Then go back to:

*Results > Graphics and Animations > Graphics > Contours*

Select {color:#990099}{*}{_}Pressure..._{*}{color}under {color:#990099}{*}{_}Contours Of{_}{*}{color}. Then select {color:#990099}{*}{_}Pressure Coefficient{_}{*}{color} from the second drop-down menu. Also, check the {color:#990099}{*}{_}Filled{_}{*}{color} checkbox and set {color:#990099}{*}{_}Levels{_}{*}{color} to 90. Then click on {color:#990099}{*}{_}Display{_}{*}{color} to update the display window.

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[Higher Resolution Image|^step6_002.png]

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Zoom in at the leading edge.

!step6_003.png|width=298,height=255!
[Higher Resolution Image|^step6_003.png]

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

h4. {color:#cc0000}Plot Skin Friction Coefficient{color}

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

*Results > Plots > XY Plot*

Change {color:#990099}{*}{_}Pressure{_}{*}{color} to {color:#990099}{*}{_}Wall Fluxes{_}{*}{color}. Then, change {color:#990099}{*}{_}Wall Shear Stress{_}{*}{color} to {color:#990099}{*}{_}Skin Friction Coefficient{_}{*}{color}. Under {color:#990099}{*}{_}Surfaces{_}{*}{color}, select {color:#990099}{*}{_}plate{_}{*}{color}. 

!step6_004.png|width=334,height=238!
 
Click {color:#990099}{*}{_}Plot{_}{*}{color}.
 
!step6_005.png|width=297,height=255!
 [Higher Resolution Image|^step6_005.png]\\

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|^cf_blasius_Re1e4.xy])

\\  !step6_006.png|width=302,height=173!
Also, you can change the symbol into lines by going to {color:#990099}{*}{_}Curves..._{*}{color} and click on the corresponding pattern that you like. Increase the {color:#990099}{*}{_}Weight{_}{*}{color} to 3 for readability. Both results should be fairly similar.

!step6_007.png|width=298,height=255!
[Higher Resolution Image|^step6_007.png]

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h4. {color:#cc0000}Plot Velocity Profiles{color}

*Results > Plots > XY Plot*

Uncheck {color:#990099}{*}{_}Position on X Axis{_}{*}{color} and check {color:#990099}{*}{_}Position on Y Axis{_}{*}{color} under Options. Under {color:#990099}{*}{_}Plot Direction{_}{*}{color}, set X to 0 and Y to 1. Under {color:#990099}{*}{_}X Axis Function{_}{*}{color}, select {color:#990099}{*}{_}Velocity..._{*}{color}Then, change {color:#990099}{*}{_}Velocity Magnitude{_}{*}{color} to {color:#990099}{*}{_}X Velocity{_}{*}{color}. Finally under {color:#990099}{*}{_}surface{_}{*}{color}, select {color:#990099}{*}{_}outlet{_}{*}{color}. Before we are ready to plot, click on the {color:#990099}{*}{_}Axes..._{*}{color} button and rescale the y-axis from 0 to 0.12. Also, check the {color:#990099}{*}{_}Major Rules{_}{*}{color} and {color:#990099}{*}{_}Minor Rules{_}{*}{color} for both axes. Remember that you must click the {color:#990099}{*}{_}Apply{_}{*}{color} button when performing changes in each axis.

Click {color:#990099}{*}{_}Plot{_}{*}{color}.
!step6_008.png|width=298,height=255!
[Higher Image Resolution|^step6_008.png]

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To compare with the Blasius solution, download the solution here. Click {color:#990099}{*}{_}Load File..._{*}{color}and select the file you just downloaded. Then plot the solutions again to display both lines on the same graph.

!step6_009.png|width=298,height=255!
[Higher Resolution Image|^step6_009.png]

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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.

h4.

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

Check the {color:#990099}{*}{_}line tool{_}{*}{color} checkbox under Options and set the initial coordinate to _(0.5,0)_ and final coordinate to _(0.5,0.5)_. Under the {color:#990099}{*}{_}New Surface Name{_}{*}{color} field, type in *x_0.5* and then click the {color:#990099}{*}{_}Create{_}{*}{color} 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 {color:#990099}{*}{_}Surfaces{_}{*}{color}, select {color:#990099}{*}{_}outlet{_}{*}{color} and {color:#990099}{*}{_}x_0.5{_}{*}{color} and {color:#990099}{*}{_}Plot

{_}{*}{color}.

!step6_010.png|width=298,height=255!
[Higher Resolution Image|^step6_010.png]

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Go to [Step 7: Refine Mesh|FLUENT - Flat Plate Boundary Layer Step 7]