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-   -   Creating an average line in paraView (http://www.cfd-online.com/Forums/openfoam-paraview/80814-creating-average-line-paraview.html)

kayoneex October 7, 2010 08:01

Creating an average line in paraView
 
Hello Users,

i have finished a simulation in OpenFoam which gets the wallShearStress over the surface. In paraFoam i can see all wallShearStresses over the whole object-surface.
Now my question: Can I lay a line over my model which gives the average of the wallShearStresses in paraView? How can i realise that in paraView? Is there a tool, for example that draws a line in x-direction over the model and gives the average of the wallShearStresses on this line?

Best regards,
Roland

kayoneex October 17, 2010 14:33

I have found it in the meantime.

chegdan October 17, 2010 16:30

how does that work again?
 
Quote:

Originally Posted by kayoneex (Post 279507)
I have found it in the meantime.

Could you share your procedure?

kayoneex October 20, 2010 07:18

Of course.

- Load your model in paraView.
- There is a tool called PlotOverLine. (Filters - Data Analysis)
- Now you can make a 2D-Line with the coordinatesyou need.
- Apply. paraView builds a graph (U or P etc..), where your sampled data is written in.
- Use the tool IntegrateVariables (Filters - Alphabetical) to get the average of this graph

Hopefully it can help.

Roland

subhkirti October 22, 2010 10:27

Average Line in Paraview
 
1 Attachment(s)
Hello kayoneex,

I am trying to get average velocity over a region and did as you suggested. However, I am not sure, that it is giving me the right values. The line is generated parallel to the x-axis at a certain y-coordinate. So, I suppose the velocity graph that I am getting is of the Ux velocity (most dominant in my case, one order of magnitude higher than Uy and Uz) in this region.

The graph that I have created using PlotOverLine gave me the following result, which is in the first graph. As you can see, the average velocity (Ux) will be in the region of 1.5. However, when I run the IntegrateVariables, I get the table, where the value of Ux is reported as 0.7932.

Am i missing something?
Quote:

Originally Posted by kayoneex (Post 279955)
Of course.

- Load your model in paraView.
- There is a tool called PlotOverLine. (Filters - Data Analysis)
- Now you can make a 2D-Line with the coordinatesyou need.
- Apply. paraView builds a graph (U or P etc..), where your sampled data is written in.
- Use the tool IntegrateVariables (Filters - Alphabetical) to get the average of this graph

Hopefully it can help.

Roland


kayoneex October 22, 2010 10:59

Hello subhkirti,

yes that is my problem too. If you look at the field, that is generated when you use Integrate Variables, you get Ux, Uy and Uz. I tried to it with the formula squr(Ux²+Uy²+Uz²), but in my case the Uy is the dominant.
In my case it the average is in the same direction, but not exactly it. Maybe somebody can help with that problem...

kayoneex October 25, 2010 06:11

@subhkirti
I tried something... IntegrateVariables gives a magnitude about 0.13 for my wallShearStress. If i look at my graph it must be around 0.06-0.07.
I typed all magnitudes ( in my case 100), you get them from PlotOverline, in Excel. With AVERAGE(A1-A100) you get the average from wallShearStress or in your Case Ux. In my case ist is about 0.066. So its right.
Now my question:
Is there an oportunity to export all magnitudes from paraView in Excel????
Or can i get the average from my magnitudes somehow with the calculator in paraView????

Please help

kayoneex October 25, 2010 07:45

export: click on the plotOverLine-magnitudes.
then file, export save as .csv-file.
you can open this file with excel.

edit the .csv-file:
- data
- text in cleaving
- cutting comma
- replace comma with point , with .
- in an empty cell: average (...-...)

subhkirti October 25, 2010 09:30

Paraview Export function
 
Well, I am having a problem there. My export option is disabled when I am using the plotOverLine. How did you do it? I tried it exactly as you mentioned it, but something is missing i guess.

Quote:

Originally Posted by kayoneex (Post 280634)
export: click on the plotOverLine-magnitudes.
then file, export save as .csv-file.
you can open this file with excel.

edit the .csv-file:
- data
- text in cleaving
- cutting comma
- replace comma with point , with .
- in an empty cell: average (...-...)


kayoneex October 25, 2010 11:38

Do you see your magnitudes in a list?
At the window of the PlotOverLine-graph in the upper right corner, there is a field called split horizontal. Click on it. Now you got a few options. Take the one which generates your magnitudes. It is one of the lower options.

Choose the whole magnitudes and click at Data - export ......

It must work...

kayoneex October 26, 2010 05:23

name of the option is: Spreadsheet View
and then in the showing-field: PlotOverLine
now you must see your magnitudes

mizzou April 22, 2016 21:50

Plotting
 
Guys,

I just simulated a 2-D fluid flow inside a pipe. Now, I'd like to plot a graph showing the variation of the radial average of certain parameter (e.g. velocity, temperature, phase fraction, etc. ) along the pipe. How can I do that? I know that I can use plot over line to show the variation of a parameter along that line. But here, I am trying to depict the variation of average value of a parameter (average in each radial direction) along the whole pipe.

Thanks,


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