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Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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Arc Length and Coordinate Transformation

Posted 2011年10月20日 GMT-4 00:22 Version 4.2 2 Replies

E. Turk
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I have a 1D Shear Rate vs arc length plot around a full circular post. Arc Length starts from 0 to pi()*D where D is the diameter of the post. I wanted to convert arc length to angle with an equation. I used ds1 , ds per manual and posts on here but it did not work.. What is the expression term for arc length that equals to Pi()*D?

(I am using Excel as a temporary solution but this required excel data export, calculation and sort data. So I wrote an excel macro but still this is extra work )

My other question is Can I place a coordinate system in the center of this circular post and get 2D stress data in polar coordinates.Expressions allow me x, y z only. Coordinate transformation menus are not very clear.


I appreciate your help.


E.Turk












2 Replies Last Post 2011年11月22日 GMT-5 13:41
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 2011年10月20日 GMT-4 02:09
Hi

in 2D, 2D-axi and 1D the arc length variable for an existing edge is "s" and runs from 0 to 1 along the edge "arrow" direction. Note that if your arc of circle is split your s is also split and not always running round in the same direction. In 3D it's more complicated as it has 3 components.

another way is tu use a variable such as r=sqrt((x-x0)^2+(y-y0)^2). Pls do not forget which frame you refer to and use the xyz and XYZ correctly, see the doc ;)

--
Good luck
Ivar
Hi in 2D, 2D-axi and 1D the arc length variable for an existing edge is "s" and runs from 0 to 1 along the edge "arrow" direction. Note that if your arc of circle is split your s is also split and not always running round in the same direction. In 3D it's more complicated as it has 3 components. another way is tu use a variable such as r=sqrt((x-x0)^2+(y-y0)^2). Pls do not forget which frame you refer to and use the xyz and XYZ correctly, see the doc ;) -- Good luck Ivar
E. Turk
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Posted: 1 decade ago 2011年11月22日 GMT-5 13:41
Thank you.
Thank you.

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