how to create intersection line of two surfaces

lostking18 · March 5, 2020, 16:39

Hi, there

I have generated a surface with constant radius and a surface inserted from external .stl file. Now I need to generate the intersection line of these two surfaces, how could I generate it in CFX post? I can’t do that with function ‘polyline’ because the .stl file created surface is not in the ‘boundary list’.
Thank you very much!

ghorrocks · March 5, 2020, 17:49

Why are you doing this in CFD-Post? This sounds like a solid modelling question to me.

lostking18 · March 5, 2020, 18:10

Hi, Glenn, thank you for your always helpful reply. I need to generate a curve in the flow field to measure the pressure profile along this curve. The intersection of these two surfaces is the easiest way for me to get this curve. Also in the practice of implementing CFX post, I always find it is helpful to have the intersection of two surfaces. But for some reason in the polyline function of CFX post, one of the surface has to been the boundary surface, which from my opinion significantly restrice the usefulness of the function. I don't why there is such restriction.

ghorrocks · March 5, 2020, 18:46

CFD-Post is a post processing software, so think from a developers point of view - why would it allow calculation of curves of arbitrary surfaces? That is not a post processing function, it is a solid modelling function.

I think you are going to have to work out the intersection line in a solid modelling package, then export the line (as points or something like that) from the solid modelling package and import them into CFD-Post.

urosgrivc · March 9, 2020, 02:11

Try this:

Make a CONTOUR on your imported stl.surface which will be coloured by RADIUS
this will give you contour lines with some radial spacing, one of these will be the line you want...
now you can select a POLYLINE and select contour which you have just made and the level you want to observe, hide the previously generated contour
now the generated poliline is hopefully where you want to observe your data
this should be it

March 5, 2020, 16:39	how to create intersection line of two surfaces	#1
lostking18 Member phd Join Date: Oct 2013 Posts: 76 Rep Power: 13	Hi, there I have generated a surface with constant radius and a surface inserted from external .stl file. Now I need to generate the intersection line of these two surfaces, how could I generate it in CFX post? I can’t do that with function ‘polyline’ because the .stl file created surface is not in the ‘boundary list’. Thank you very much!

March 5, 2020, 17:49		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,854 Rep Power: 144	Why are you doing this in CFD-Post? This sounds like a solid modelling question to me. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

March 5, 2020, 18:46		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,854 Rep Power: 144	CFD-Post is a post processing software, so think from a developers point of view - why would it allow calculation of curves of arbitrary surfaces? That is not a post processing function, it is a solid modelling function. I think you are going to have to work out the intersection line in a solid modelling package, then export the line (as points or something like that) from the solid modelling package and import them into CFD-Post. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

March 9, 2020, 02:11		#5
urosgrivc Senior Member urosgrivc Join Date: Dec 2015 Location: Slovenija Posts: 365 Rep Power: 11	Try this: Make a CONTOUR on your imported stl.surface which will be coloured by RADIUS this will give you contour lines with some radial spacing, one of these will be the line you want... now you can select a POLYLINE and select contour which you have just made and the level you want to observe, hide the previously generated contour now the generated poliline is hopefully where you want to observe your data this should be it Last edited by urosgrivc; March 10, 2020 at 03:53.

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March 5, 2020, 18:10		#3
lostking18 Member phd Join Date: Oct 2013 Posts: 76 Rep Power: 13	Hi, Glenn, thank you for your always helpful reply. I need to generate a curve in the flow field to measure the pressure profile along this curve. The intersection of these two surfaces is the easiest way for me to get this curve. Also in the practice of implementing CFX post, I always find it is helpful to have the intersection of two surfaces. But for some reason in the polyline function of CFX post, one of the surface has to been the boundary surface, which from my opinion significantly restrice the usefulness of the function. I don't why there is such restriction.