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Extract Center Line from 3D Geometry for Sweep Operation

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Hello everyone,

I am losing my mind trying to find the center line of the Geometry of an Artery in order to Sweep the ellipsoid at the begiining along this line. (as in screenshot) What kind of operation can I use here? In the results part of my simulation the data of the streamlines etc can be seen but I cant figure out how to get a 3D spline based on the interpolation of the outer arterial wall.

Help would be very much appreciated! :-)



3 Replies Last Post 15.10.2021, 11:32 GMT-4
Jeff Hiller COMSOL Employee

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Posted: 3 years ago 13.10.2021, 11:55 GMT-4
Updated: 3 years ago 13.10.2021, 13:14 GMT-4

Hello Mathias,

This is a bit of an odd question for me to ask, but how do you define the centerline in this case? It would seem that you could create different curves that all run approximately down the middle of the artery but all differ from one another slightly, depending on the exact way you create them.

In any case, I have a hunch that you could create one such curve using the Wall Distance Interface (see this link ) in some way.

Jeff

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Jeff Hiller
Hello Mathias, This is a bit of an odd question for me to ask, but how do you define the centerline in this case? It would seem that you could create different curves that all run approximately down the middle of the artery but all differ from one another slightly, depending on the exact way you create them. In any case, I have a hunch that you could create one such curve using the Wall Distance Interface (see [this link](https://www.comsol.com/blogs/tips-using-wall-distance-interface/) ) in some way. Jeff

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Posted: 3 years ago 15.10.2021, 10:17 GMT-4

Hello Jeff,

thanks for the advice. I am aware that the different curves might differ from one another but thats fine for the purpose I am using it for. Unfortunately I couldnt figure out how to implement the Wall distance interface in a proper fashion since I am unsure how to set up the correct values for distance equation, periodic condition, wall distance continuity etc.

Is there a way to extract the coordinates of a streamline thats close to the center somehow? This would be sufficient for my simulation so I can use it to sweep the "outer arterial wall" and assign material properties along that "tube".

I appreciate your help

Hello Jeff, thanks for the advice. I am aware that the different curves might differ from one another but thats fine for the purpose I am using it for. Unfortunately I couldnt figure out how to implement the Wall distance interface in a proper fashion since I am unsure how to set up the correct values for distance equation, periodic condition, wall distance continuity etc. Is there a way to extract the coordinates of a streamline thats close to the center somehow? This would be sufficient for my simulation so I can use it to sweep the "outer arterial wall" and assign material properties along that "tube". I appreciate your help

Jeff Hiller COMSOL Employee

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Posted: 3 years ago 15.10.2021, 11:32 GMT-4
Updated: 3 years ago 15.10.2021, 13:09 GMT-4

Hi Mathias,

Perhaps I should have asked you what you need the centerline for. Because if what you ultimately want to do is to turn your single domain into one that represents the wall of the artery and one that represents the inside of the artery, then there is a very easy way to do it that does not require the centerline: use an asymmetric Thicken operation. The attached file illustrates what I mean, with your complex shape replaced by a cylinder.

Best,

Jeff

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Jeff Hiller
Hi Mathias, Perhaps I should have asked you what you need the centerline for. Because if what you ultimately want to do is to turn your single domain into one that represents the wall of the artery and one that represents the inside of the artery, then there is a very easy way to do it that does not require the centerline: use an asymmetric Thicken operation. The attached file illustrates what I mean, with your complex shape replaced by a cylinder. Best, Jeff

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