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gilberto December 5, 2001 07:54

Polyline in CFX-POST
Hi everyone,

How do you create a polyline in CFX-POST???If it is not an intersection between and object and a boundary,the only other option is Create Polyline From File!!!

The instructions are really confusing in the Manual,can any of you give me a clear example of creating a line,for instance, from point (1 2 3) to (4 5 6).

If any of you have come across this roblem,please let me know,thanks very much!!!

cfd guy December 5, 2001 11:15

Re: Polyline in CFX-POST
Hi gilberto,
I have never used CFX-POST, however in CFX-Visualize which comes with CFX-5, a polyline file is a set of coordinate points [x y z]. I'll show you below:

0. 0.0 -0.1
0. 0.1 -0.1
0. 0.2 -0.1
0. 0.3 -0.1
In the example above I created a line along the X axis at a certain Z position. You can easily make points like this (a function) in applications like Excel, Origin, etc. But remember to save them in an ASCII file.

Hope this helps,
cfd guy

gilberto December 5, 2001 14:25

Re: Polyline in CFX-POST

But the important question is,how do you do that??(Meaning saving it as an ASCII file),and most important, is the program going to recognise that format??

Robin Steed December 5, 2001 20:46

Re: Polyline in CFX-POST
Hi Gilberto!!!!,

Ease up on the emotion, is everything a crisis????

At this stage, it is not possible to create a polyline other than the method stated above.

What is your need for the polyline? Are you trying to extract data along it?


gilberto December 6, 2001 11:57

Re: Polyline in CFX-POST
Hi, Robin!!!

No, of course it was not a crisi,although sometimes it seems, but it is simply the way I express myself, with exclamation signs and so on, but it was not really a critical question.

Yes, what I wanted was to extract some values along one special line,difining two points in it.

My very important questions qill come soon, when I start to make my rotor rotate, and I will possibly find some difficulties in that.I count on you,my friend.

Thanks for your help,and I will try to make my queries a bit more calmed,, ha ha ha

cfd guy December 6, 2001 12:11

Re: Polyline in CFX-POST
Hi gilberto,
As I stated above, I just forgot one thing, at the beggining of the polyline file you MUST specify the number of points that properties will be interpolated. Example:
Open your NOTEPAD (the same which comes with MS-Windows) and put the follow numbers:
0.1 -0.5 -1.0
0.1 -0.4 -1.0
0.1 -0.3 -1.0
0.1 -0.2 -1.0
Now save the file and put it into CFX-POST and you will realize that a line at constant X and Z position will be created. And when you export the desired properties, 4 values will appear 'cause you only defined 4 points.
Still in doubt? Regards,
cfd guy

gilberto December 6, 2001 12:42

Re: Polyline in CFX-POST
No doubts whatsoever!!!!

Thank you, mate!!


Robin Steed December 6, 2001 23:52

Re: Polyline in CFX-POST
Hi Gilberto,

If you don't want to create the points and import the polyline, you could create a sampling plane and restrict it's range to get the points you wish.

Personally, I would just make the points and import them.

Regards, Robin

gilberto December 7, 2001 05:35

Re: Polyline in CFX-POST
I already did that, I created the points, and evrything, but when I create the chart, I still cannot see any curve in the chart.Is that because the number of points I created, or something like that?



gilberto December 7, 2001 05:38

Re: Polyline in CFX-POST
I did it, but when I create the chart, I still cnnot see anything but the axes.Is that because I have to create a bigger number of points???

Obrigado,meu amigo!!

mike December 7, 2001 13:50

Re: Polyline in CFX-POST
Sounds like you need to define some lines in your file. The list of points is just that - points. To create lines you define lines that connect the points. This example create 3 lines (in 1 Polyline object) that form a trangle

0 0 0 0 0.05 0.25 0 0 0.25 # Lines 0 1 1 2 2 0

i.e the 1st line connects point 0 to point 1, the 2nd line connects point 1 to point 2 etc

Hope this helps Mike

mike December 7, 2001 13:56

Re: Polyline in CFX-POST
ok, the line breaks didn't come out in that last respones - try again

0 0 0

0 0.05 0.25

0 0 0.25

# Lines

0 1

1 2

2 0

If this doesn;t come out then there's a line break after every 3rd number before "# Lines", then one after every 2nd number after # Lines.


gilberto December 7, 2001 13:59

Re: Polyline in CFX-POST
Well, apparently CFX Post did actually create a polyline out of my file with the points.Now, the problem is a bit different,because after defining the polyline,I create a chart, but no lines are plotted in my X-Y chart.

Thanks for your help anyway, mate

cfd guy December 7, 2001 14:08

Re: Polyline in CFX-POST
Hi gilberto,
As I said, I still did not have any contact with CFX-POST and I don't know what is a chart, at least Visualize doesn't have this feature.

PS.: Seu nome nunca me enganou, tinha fortes suspeitas de vc ser brasileiro (ou ao menos fala portuguÍs).

cfd guy

gilberto December 7, 2001 14:36

Re: Polyline in CFX-POST
Non,eu sou espanyol!!!

But I used to live very close to Galicia in Northern Spain!!!

Regards,my friend

steve December 7, 2001 15:20

Re: Polyline in CFX-POST
Is the polyline positioned along an edge of the doimain (i.e. along x=0). If so then the polyline may fall outside the domain due to rounding errors in the grid. If this is the case then no values would be plotted on the chart. This would also explain why the plane intersection technique for creating the polyline failed.

If this is the case then try shifting the values for the polyline slightly. i.e. x = 0.0001 instead of x=0.0.

mike December 7, 2001 16:00

Re: Polyline in CFX-POST
Just as a correction, you don't have to create Lines. If no lines are specified then subsequent points are joined together.

Robin Steed December 8, 2001 11:32

Re: Polyline in CFX-POST
Hi Gilberto,

Post will only return values at the vertices on the polyline. If you want values at 20 points, from [0,0,0] to [0,0,1] for instance, you must create a polyline which is made up from points: [0,0,], [0,0,.05], [0,0,.1], ... [0,0,.95], [0,0,1].

The line you see in post is really just for visualization, the points themselves are the locators from which the data is returned.

Regards, Robin

gilberto December 8, 2001 15:51

Re: Polyline in CFX-POST
That explains everything!!!Fine, my friend, I know what to do now,now it is working!!!

As usual, you have been of great help!Thanks a lot,amigo!!!

Kaki January 6, 2015 09:18

Dear All,

I would like to create a curved polyline in CFX POST. Some of the answers above were very helpful to create the txt-File. But now my problem is that it seems to be not possible to create a curved polyline in POST, because a straight line is working and i am able to export the velocity on this line.

Does anyone has a hint why it doesn't work on a curved polyline and what's an alternative possibility? Thanks in advance =)

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