Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Use coordinates of edge as a variable?

Please login with a confirmed email address before reporting spam

Hello,

is it possible to extract coordinates (or other quantities) along a geometry edge and use these as simulation variable (e.g. constraint for other nodes)?

For example, it is possible to plot the x-position along an edge, say as x(z). I would now like to use the movement of a geometry edge (ALE mesh movement) - which already works well - as "prescribed geometry displacement" for an adjacent surface element of the same geometry.

I think something similar to an "edge probe" - but without integration or summation along the edge - would solve my problem, but is there anything like that?

Best regards,
Jens Schüttler

1 Reply Last Post 17.10.2010, 05:03 GMT-4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 17.10.2010, 05:03 GMT-4
Hi

in V4 you have a simple way to plot a valuer along an edge, or the coordinates.
A simple example:
lets say you make a simple 3D structural simulation of a block of 1[m] side, made of steel
E=200GPa, nu=0.3, rho=[7750kg/m^3]
You fix BC 1 and you apply a body load to the block 1, of Fz=-g_const*solid.rho
You then solve this with a coarse mesh.
By right-clicking on the "Results Data Set" you add an "Edge 3D" solution subset, and you select edge 5 (or any one not fixed by heritage)
You then right-click "Results" and select "1D Plot Group" and select the source as the "Edge 3D" Data Set
You add a "Line Graph" and select "w" as an expression and ou "Plot"
Thenou can change the X axis from arc length "s" to Expression and use x or X (ok for edge 5 of the block) in this case as edge 5 is along x ther is no real difference with the arc length, but it is easy to understand what would happen if the block had a skewed orientation.

For the solving process, you need to use mapping operators to get the coordinates of one edge applying effects elsewhere, see the doc and try with really "simplest" possible examples, as this is a little tricky to catch, at least in the beginning

--
Good luck
Ivar
Hi in V4 you have a simple way to plot a valuer along an edge, or the coordinates. A simple example: lets say you make a simple 3D structural simulation of a block of 1[m] side, made of steel E=200GPa, nu=0.3, rho=[7750kg/m^3] You fix BC 1 and you apply a body load to the block 1, of Fz=-g_const*solid.rho You then solve this with a coarse mesh. By right-clicking on the "Results Data Set" you add an "Edge 3D" solution subset, and you select edge 5 (or any one not fixed by heritage) You then right-click "Results" and select "1D Plot Group" and select the source as the "Edge 3D" Data Set You add a "Line Graph" and select "w" as an expression and ou "Plot" Thenou can change the X axis from arc length "s" to Expression and use x or X (ok for edge 5 of the block) in this case as edge 5 is along x ther is no real difference with the arc length, but it is easy to understand what would happen if the block had a skewed orientation. For the solving process, you need to use mapping operators to get the coordinates of one edge applying effects elsewhere, see the doc and try with really "simplest" possible examples, as this is a little tricky to catch, at least in the beginning -- Good luck Ivar

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.