Step 6: Results
Please make sure your project is saved in Workbench. Double click on Results in the Project Schematic window. This will open CFD-Post (the program used to analyze results from FLUENT computation.)
Overview
You may have noticed in previous sections, that the pipe looks extremely long and thin on the screen. In fact, due to the symmetry condition of the experiment, we have only modeled half the pipe in our analysis. To be able to make full use of the results, we must:
1) Generate the results for the parameter investigated (e.g. temperature, pressure, velocity)
2) Mirror the result to reflect the result of the full pipe
3) Adjust the scaling of the resulting graphs so that the variation of the pipe in y direction is more pronounced.
Temperature Contour
Our first challenge is the temperature contour. On the top menu, click on contour OK when done. On the left hand side, under Details of Temperature Contour, select the appropriate parameter to obtain the result we want. Next to Locations, select periodic 1. Select Temperature for Variable. Enter 100 for # of Contours.
Next, click on the View tab. We would like to specify the look of the contour plot. Select Apply Reflection/Mirroring. Select ZX Plane next to Method. This will reflect our model in the ZX Plane and enable us to look at the temperature contour at the cross section of of the pipe. Next, select Apply Scale. Enter 30 for y-axis. This will stretch our model in the y direction. This will enable us to better view how the flow is mixed in the whole pipe. Finally click Apply.
After you click Apply, you will see that under Outline > User Locations and Plots, Temperature Contour is created. You will also see that the Temperature Contour is plotted in the Graphics window on the right. Under Outline > User Locations and Plots, uncheck Wireframe to see just the Temperature Contour in the Graphics window.
Is the flow well mixed at the end of adiabatic mixing section?
Velocity Vectors
On the top menu, click on vector OK. Under Details of Velocity Vector, select periodic 1 next to Locations.
Next, we will specify how the arrow will appear. Click on Symbol tab. Enter 0.05 for Symbol Size.
Finally click Apply. You will see that under Outline > User Locations and Plots, Velocity Vector is created. Uncheck Temperature Contour so that Graphics window shows just the Velocity Vector plot.
Velocity vectors in the first section showing flow development.
Pressure Plot
Now let's us look at the pressure variation at the centerline. First, we will create a line call centerline.
Insert > Location > Line
Name it "Centerline" and click OK. On the lower left panel, you will see Details of Centerline. Enter the following coordinates.
Point 1 (0,0,0)
Point 2 (6.096,0,0)
Enter 50 for Samples. (This will be the number of sample points used when plotting data)
Click Apply.
You will see centerline created under User Locations and Plots.
Next, we will create a chart using this Location data.
Insert > Chart
Enter "Axial Pressure" as Name. You will see Details of Axial Pressure appear on the lower left panel. Under General, give the chart Title as "Pressure Variation along Pipe Axis".
Now click on Data Series tap to specify the location of the chart data. Create a new data series . Change the name from Series 1 to FLUENT. Under Data Source, specify Centerline as Location.
We would also like to compare our simulation result with experimental data. Experimental data is can be downloaded here. Download it to the directory that you like. Now, click a new data series . Name it Experiment. Under Data Source, select File and browse to the downloaded experimental data.
Now we will specify the X Axis parameter. Click on X Axis tab. Next to Variable, choose X.
Now we will specify the Y Axis parameter. Click on Y Axis tab. Next to Variable, choose Pressure.
Now we will specify how we want to the chart to display. The default setting is to display the data series in lines. Since we only have 3 experimental points, we want them to be displayed in data points. Click on Line Display. Then click on experimental tab. Next to Line Style, change Automatic to None. Next to Symbols, change None to Diamond. Change the color to red. Click Apply. You will see Axial Pressure created under Report in the Outline tab.
This is what you should see in the Graphics window.
Does the simulation result compares well with the experimental data?
Centerline Temperature Plot
Now let's look at the temperature variation along the centerline.
Insert > Chart
Enter "Centerline Temperature" as Name. You will see Details of Centerline Temperature appear on the lower left panel. Under General, give the chart Title as "Temperature Variation along Pipe Axis".
Now click on Data Series tap to specify the location of the chart data. Create a new data series . Change the name from Series 1 to FLUENT. Under Data Source, specify Centerline as Location.
We would also like to compare our simulation result with experimental data. Experimental data is can be downloaded here. Download it to the directory that you like. Now, click a new data series . Name it Experiment. Under Data Source, select File and browse to the downloaded experimental data.
Now we will specify the X Axis parameter. Click on X Axis tab. Next to Variable, choose X.
Now we will specify the Y Axis parameter. Click on Y Axis tab. Next to Variable, choose Temperature.
Now we will specify how we want to the chart to display. The default setting is to display the data series in lines. Since we only have 3 experimental points, we want them to be displayed in data points. Click on Line Display. Then click on experimental tab. Next to Line Style, change Automatic to None. Next to Symbols, change None to Diamond. Change the color to red. Click Apply. You will see Centerline Temperature created under Report in the Outline tab.
This is what you should see in the Graphics window.
Does the simulation result compares well with the experimental data?
Wall Temperature Plot
Now let's us look at the temperature variation along the wall. First, we will create a line call wall.
Insert > Location > Line
Name it "Wall" and click OK. On the lower left panel, you will see Details of Wall. Enter the following coordinates.
Point 1 (0,0.0294,0)
Point 2 (6.096,0.0294,0)
Enter 50 for Samples. (This will be the number of sample points used when plotting data)
Click Apply.
You will see wall created under User Locations and Plots.
Next, we will create a chart using this Location data.
Insert > Chart
Enter "Wall Temperature" as Name. You will see Details of Wall Temperature appear on the lower left panel. Under General, give the chart Title as "Wall Temperature".
Now click on Data Series tap to specify the location of the chart data. Create a new data series . Change the name from Series 1 to FLUENT. Under Data Source, specify Wall as Location.
We would also like to compare our simulation result with experimental data. Experimental data is can be downloaded here. Download it to the directory that you like. Now, click a new data series . Name it Experiment. Under Data Source, select File and browse to the downloaded experimental data.
Now we will specify the X Axis parameter. Click on X Axis tab. Next to Variable, choose X.
Now we will specify the Y Axis parameter. Click on Y Axis tab. Next to Variable, choose Temperature.
Now we will specify how we want to the chart to display. The default setting is to display the data series in lines. Since we only have 3 experimental points, we want them to be displayed in data points. Click on Line Display. Then click on experimental tab. Next to Line Style, change Automatic to None. Next to Symbols, change None to Diamond. Change the color to red. Click Apply. You will see Axial Pressure created under Report in the Outline tab.
This is what you should see in the Graphics window.
Does the simulation result compares well with the experimental data?
Axial Velocity Profile
Now let's us look at the axial velocity profile at various location in the pipe. We are interested in the flow development before the heated section and would like to observe how heat addition in the heated section will affect the flow development. To do this, let's start with investigation the flow before the heated section.
Axial Velocity Profile before Heated Section
The heated section is from 1.83m to 4.27m. Let's create 4 lines before 1.83m in the pipe.
Insert > Location > Line
Name it "Inlet" and click OK. On the lower left panel, you will see Details of Inlet. Enter the following coordinates.
Point 1 (0,0,0)
Point 2 (0,0.0294,0)
Enter 50 for Samples. (This will be the number of sample points used when plotting data)
Click Apply.
Create Preheat 1.
Insert > Location > Line
Name it "Preheat 1" and click OK. On the lower left panel, you will see Details of Preheat 1. Enter the following coordinates.
Point 1 (0.6,0,0)
Point 2 (0.6,0.0294,0)
Enter 50 for Samples. (This will be the number of sample points used when plotting data)
Click Apply.
Continue the same step for creating line Preheat 2 (x=1.2m), Preheat 3 (x=1.8m).
Check that you have the following under Outline.
Now we will have enough interval to look at the flow development before the heating. Let's create a chart to investigate this.
Insert > Chart
Enter "First Section Axial Velocity Profile" as Name. You will see Details of First Section Axial Velocity Profile appear on the lower left panel. Under General, give the chart Title as "Axial Velocity Profile".
Now click on Data Series tap to specify the location of the chart data. Create a new data series . Under Data Source, specify Inlet as Location. Change the name to Inlet. Continue adding Data Source until we added all Inlet, Preheat 1, Preheat 2, and Preheat 3. Name them according to the figure shown below.
Now we will specify the X Axis parameter. Click on X Axis tab. Next to Variable, choose Velocity u. Next we will specify the Y Axis parameter. Click on Y Axis tab. Next to Variable, choose Y. Click Apply. You will see First Section Axial Velocity Profile created under Report in the Outline tab.
This is what you should see in the Graphics window.
Axial Velocity Profile before and after Heated Section
Let's create lines after heated section
Insert > Location > Line
Name it "Postheat 1" and click OK. On the lower left panel, you will see Details of Postheat 1. Enter the following coordinates.
Point 1 (4.27,0,0)
Point 2 (4.27,0.0294,0)
Enter 50 for Samples. (This will be the number of sample points used when plotting data) Click Apply.
Create Postheat 2.
Insert > Location > Line
Name it "Postheat 2" and click OK. On the lower left panel, you will see Details of Postheat 2. Enter the following coordinates.
Point 1 (5,0,0)
Point 2 (5,0.0294,0)
Enter 50 for Samples. Click Apply.
Continue the same step for creating line Outlet (x=6.096m)
Check that you have the following under Outline.
Now we will have enough interval to look at the flow development before and after the heating. Let's create a chart to investigate this.
Insert > Chart
Enter "Second Section Axial Velocity Profile" as Name. You will see Details of Second Section Axial Velocity Profile appear on the lower left panel. Under General, give the chart Title as "Axial Velocity Profile".
Now click on Data Series tap to specify the location of the chart data. Create a new data series. Under Data Source, specify Preheat 3 as Location. Change the name to x=1.8m. Continue adding Data Source until we added all Preheat 3, Postheat 1, Postheat 2, and Outlet. Name them according to the figure shown below.
Now we will specify the X Axis parameter. Click on X Axis tab. Next to Variable, choose Velocity u. Next we will specify the Y Axis parameter. Click on Y Axis tab. Next to Variable, choose Y. Click Apply. You will see First Section Axial Velocity Profile created under Report in the Outline tab.
This is what you should see in the Graphics window.
The flow is accelerated in the heated section.
Temperature Profile
Now let's us look at the temperature profile before and after the heating section.
Insert > Chart
Enter "Temperature Profile" as Name. You will see Details of Temperature Profile appears on the lower left panel. Under General, give the chart Title as "Temperature Profile".
Now click on Data Series tab to specify the location of the chart data. Create a new data series. Under Data Source, specify Preheat 3 as Location. Change the name to x=1.8m. Similarly, add the locations: Preheat 3, Postheat 1, Postheat 2, and Outlet. Name them according to the figure shown below.
Now we will specify the X Axis parameter. Click on X Axis tab. Next to Variable, choose Temperature. Next we will specify the Y Axis parameter. Click on Y Axis tab. Next to Variable, choose Y. Click Apply. You will see Temperature Profile created under Report in the Outline tab.This is what you should see in the Graphics window.
The plot shows temperature is nearly uniform at the outlet (end of mixing section).
Go to Step 7: Verification & Validation