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!!!

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

Re: Polyline in CFX-POST
 

Thanks,mate!!!

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??

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?

Robin

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

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:
4
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

Re: Polyline in CFX-POST
 

No doubts whatsoever!!!!

Thank you, mate!!

Regards

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

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?

Regards,

Gilberto

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!!

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

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.

Mike

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

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 português).

Regards,
cfd guy

Re: Polyline in CFX-POST
 

Non,eu sou espanyol!!!

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

Regards,my friend

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.

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.

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

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!!!

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 =)

What do you mean with curved polyline?
To my understanding a Polyline is a line that is built from small segments connecting the points defining the path of the line. But these segments are always a straight line. So for a curved shape you just need to define enough points that are very close to each other and tracing a "curved line"....
At least, that's how I understand the polyline.

Thanks a lot for your help monkey1! First i used a straight line and from this i tried to approximate a curved line (involute). Now it's working the way you said, thanks again!

But now i have another problem with this line. Because i would like to compare the effect of the relativ velocity on a liquid thread. For this I would like to put vectors on this line (that's not the problem) but they need to be orthogonal. Does anyone know how i can do this in ansys cfx post?!

Orthogonal to what? the polyline?
Don't think that this will work, as the vector representation always shows you the orientation/direction of the vector. So if the porientation of your flow field is not orthogonal then you will not get an orthogonal vector.

create polyline
 

Hi all.
I have a problem to create a polyline in cfx post.
I modele a ducted propeller and analysis it. Now, I want to create a polyline about one blade but I just can create a isosurface and a polyline by intersect of isosurface and propeller. In this way, polyline create about all of blades but I need create it about one blade to show a chart for pressure distribution on one blade.
Help me please:(

Maybe you can try the following:

A polyline can be drawn from a contour. So try to put a contour on the one single blade and let the polyline be drawn from it. But this will only work if you have separate surfaces for each blade...or you will habe to define a csv file where you save the coordinates of the points of the polyline and then you draw it from file.

Hi monkey1
Unfortunatly I didn't separate surfaces. So I think that I must define coordinates of points.
Thank you so much :rolleyes:

Hi

I have a curved pipe. I want to make a chart which has curved polyline at the bottom of the green surface as x-axis. I have tried the boundary intersection method in polyline. But it doesn't work.

Does anyone has any idea to make the curved?

Thanks in advance

Polyline @cfd post
 

Hii gilberto,

i gone through your post, i hope you are good in polyline.

Can you help me in creating curved polyline over the circumference of the cylinder.