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Degree of Freedom

Posted 2022年5月17日 GMT+2 16:03Structural & Acoustics, Computational Fluid Dynamics (CFD), Structural Mechanics3 Replies

Hitesh Kumar Sinha
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Hi, I am using 4 quadratic element in 2D square geometry for calculation of temperature. I get9 values of temperatureat each node using functionmpheval, but when i usefuction mphmatrixto getK matrix it come 25x25. It says number ofdegree of freedom is 25.

How it is possible for scalar 2D Heat conduction problem? The K matrix should also be 9x9.

I am unable to find in document regarding degree of freedom. and internal degree of freedom Please help.

Hitesh Kumar Sinha Thank You

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3 Replies Last Post 2022年5月23日 GMT+2 11:36
Henrik Sönnerlind COMSOL Employee

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Posted: 2 years ago 2022年5月18日 GMT+2 13:01

If you look underDiscretizationin theHeat Transfer in Solidsnode, you will see that the shape functions used areQuadratic Lagrange, so there are 25 nodes in the mesh.

If you want to visualize the nodes, add aMeshplot in any plot group, and select the physics interface in theNode pointsdrop-down menu.

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Henrik Sönnerlind
COMSOL
If you look under *Discretization* in the *Heat Transfer in Solids* node, you will see that the shape functions used are *Quadratic Lagrange*, so there are 25 nodes in the mesh. If you want to visualize the nodes, add a *Mesh* plot in any plot group, and select the physics interface in the *Node points* drop-down menu.
Lars Gregersen COMSOL Employee

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Posted: 2 years ago 2022年5月23日 GMT+2 10:35

Hi Hitesh

mpheval assumes first order elements by default.

If you set 'refine' to 2 then you'll get the second order information - and usually much larger matrices.

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Lars Gregersen
Comsol Denmark
Hi Hitesh mpheval assumes first order elements by default. If you set 'refine' to 2 then you'll get the second order information - and usually much larger matrices.
Hitesh Kumar Sinha
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Posted: 2 years ago 2022年5月23日 GMT+2 11:36

Thank Henrik and Lars. Thank you so much for your reply. I helped me alot, thank once again for your guidence

Thank Henrik and Lars. Thank you so much for your reply. I helped me alot, thank once again for your guidence

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