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Coordinate Dependant Variables and Deformation

Posted Mar 9, 2020, 12:22 p.m. EDT Structural & Acoustics, Fluid & Heat, Parameters, Variables, & Functions Version 5.4 3 Replies

Thomas Scone
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Hi there. I've had a bit of a look around and I couldn't find an answer to a relatively simple underlying part of COMSOL's variables.

If I define a load (in this case a volume force) on a mesh element/node using a coordinate dependant variable will that load be updated as the mesh deforms? I.e after a step in the solution will the load be updated using the new coordinates of the mesh element/node it is acting on?

Thanks for taking the time to read,

3 Replies Last Post Mar 12, 2020, 4:58 a.m. EDT
Edgar J. Kaiser Certified Consultant
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Posted: 5 years ago Mar 9, 2020, 1:31 p.m. EDT

Thomas,

You must use a moving mesh to achieve that.

Cheers Edgar

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Thomas, You must use a moving mesh to achieve that. Cheers Edgar
Henrik Sönnerlind COMSOL Employee

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Posted: 5 years ago Mar 9, 2020, 4:23 p.m. EDT
Updated: 5 years ago Mar 12, 2020, 5:19 a.m. EDT

If you write a coordinate with uppercase letters (X,Y,Z), it is in material frame (original coordinates). If you use lowercase (x,y,z) it is in spatial frame (room fixed coordinates).

If you use geometric nonlinearity (for structural mechanics) or a moving mesh, then the frames will differ, and this convention becomes important.

Say that you have an edge originally located at 0\<x\<1, and apply two loads to it: 3*X and 5*x.

Now the edge is translated to 1\<x\<2. The first load still varies from 0 to 3, while the second one now varies from 5 to 10.

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Henrik Sönnerlind
COMSOL
If you write a coordinate with uppercase letters (X,Y,Z), it is in material frame (original coordinates). If you use lowercase (x,y,z) it is in spatial frame (room fixed coordinates). If you use geometric nonlinearity (for structural mechanics) or a moving mesh, then the frames will differ, and this convention becomes important. Say that you have an edge originally located at 0\
Thomas Scone
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Posted: 5 years ago Mar 12, 2020, 4:58 a.m. EDT
Updated: 5 years ago Mar 12, 2020, 5:20 a.m. EDT

Thank you for helping me out with that. I will try and implement it soon. Fingers crossed it goes smoothly and I can move onto the next stage of my project.

Thank you for helping me out with that. I will try and implement it soon. Fingers crossed it goes smoothly and I can move onto the next stage of my project.

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