Author: John Singleton and Rajesh Bhaskaran, Cornell University

Problem Specification
1. Pre-Analysis & Start-up
2. Geometry
3. Mesh
4. Setup (Physics)
5. Solution
6. Results
7. Verification & Validation

This page of this tutorial is currently under construction. Please check back soon.

Click here for the FLUENT 6.3 version.

Step 6: Results

Velocity Vectors

One can plot vectors in the entire domain, or on selected surfaces. Here, the vectors will be plotted for the entire domain. First, click on Graphics & Animations . Next, double click on Vectors which is located under Graphics. Then, click on Display in the Vectors menu. You should obtain, the following output. 


https://confluence.cornell.edu/download/attachments/118771111/VectPlot_Full.png


You can use the wheel button of the mouse to zoom into the region that closely surrounds the plate, to get a better view of the boundary layer velocities. 


https://confluence.cornell.edu/download/attachments/118771111/VectPlot2_Full.png



Outlet Velocity Profile

In this section we will first plot the variation of the x component of the velocity along the outlet. Then we will plot the Blasius solution and to see how the numerical solution compares. In order to start the process (Click) Results > Plots > XY Plot... > Set Up.. as shown below. 


https://confluence.cornell.edu/download/attachments/118771111/xyplotsetup_Full.png


In the Solution XY Plot menu make sure that Position on Y Axis is selected , and X is set to 0 and Y is set to 1. This tells FLUENT to plot the y-coordinate value on the ordinate of the graph. Next, select Velocity... for the first box underneath X Axis Function and select X Velocity for the second box. Please note that X Axis Function and Y Axis Function describe the x and y axes of the graph, which should not be confused with the x and y directions of the geometry. Finally, select outlet under Surfaces since we are plotting the x component of the velocity along the outlet. This finishes setting up the plotting parameters. Your Solution XY Plot menu should look exactly the same as the following image. 


https://confluence.cornell.edu/download/attachments/118771111/SolXY1_Full.png


Now, click Plot. The plot of the x component of the velocity as a function of distance along the outlet now appears. 


https://confluence.cornell.edu/download/attachments/118771111/XVelPlot1_Full.png


In order to increase the legibility of the graph, we will plot the data as a line rather than points. To turn on the line feature, click on Curves... in the Solution XY Plot menu. Then, set Pattern to Center, set the Weight to 2 and select nothing for Symbol, as shown below. 


https://confluence.cornell.edu/download/attachments/118771111/CurveMen_Full.png


Next, click Apply in the Curves - Solution XY Plot menu. Next, close the Curves - Solution XY Plot menu.

Now, the range of the y axis will be truncated, as we are not interested in far field velocity. Furthermore, the grid lines will be turned on. In order to implement these two changes. First click Axes in the Solution XY Plot menu. Next, select Y for Axis, deselect Auto Range, select Major Rules, select Minor Rules. Then, set Minimum to 0 and set Maximum to 1.2. Your Axes - Solution XY Plot menu, should look exactly like the image below. 


https://confluence.cornell.edu/download/attachments/118771111/AxesMen1_Full.png


Then, click Apply in the Axes - Solution XY Plot menu. Now, select X for Axis and select Major Rules and Minor Rules, as shown below. 


https://confluence.cornell.edu/download/attachments/118771111/Axes2_Full.png


Next, click Apply in the Axes - Solution XY Plot menu. Close the Axes - Solution XY Plot menu. Now, click Plot menu in the Solution XY Plot menu. You should obtain the following output. 


https://confluence.cornell.edu/download/attachments/118771111/Plot5_Full.png


It is of interest to compare the numerical velocity profile to the velocity profile obtained from the Blasius solution. In order to plot the theoretical results, first click here to download the necessary file. Save the file to your working directory. Next, go to the Solution XY Plot menu and click Load File... and select the file that you just downloaded, BlasiusU.xy. Lastly, click Plot in the Solution XY Plot menu. You should then obtain the following figure. 


https://confluence.cornell.edu/download/attachments/118771111/Plot6_Full.png


Lastly, select Write to File located under Options in the Solution XY Plot menu. Then, click Write.... When prompted for a filename, enter XVelOutlet.xy and save the file in your working directory.


Pressure Coefficients

In this section we will create contour plots for the pressure coefficients. Before we begin, we must first set the reference values for velocity. In order to do so, first click on Reference Values then set Compute from to inlet, as shown below. 


https://confluence.cornell.edu/download/attachments/118771111/CompInlet_Full.png


Next, click on Graphics and Animations, then double click on Contours, as shown below. 


https://confluence.cornell.edu/download/attachments/118771111/ContPlot_Full.png


In the Contours menu, set Contours of to Pressure... and set the box below to Pressure Coefficient. Next, select Filled and set Levels to 90. Your Contours menu should look exactly like the following image. 


https://confluence.cornell.edu/download/attachments/118771111/Contou_Full.png


Lastly, click Display in the Contours menu to generate the contour plot. You should obtain the following output. 


https://confluence.cornell.edu/download/attachments/118771111/ContP1_Full.png


You can zoom then zoom in to the leading edge of the plate with the wheel mouse button as shown below. 


https://confluence.cornell.edu/download/attachments/118771111/ContZoom_Full.png



Skin Friction Coefficient

Here, the skin friction coefficient will be plotted as a function of distance along the 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.
 

 

https://confluence.cornell.edu/download/attachments/118771111/step6_005.png?version=1


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.

https://confluence.cornell.edu/download/attachments/118771111/step6_007.png?version=1



Drag

Now, we will obtain the drag on the plate.



Go to Step 7: Verification & Validation

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