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HOW TO DEFINE A VARIABLE IN COMSOL?

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Hi there,
How and where from can i define the following variable for subdomain in comsol3.5a?

PHYSICS SETTINGS
Define the following parameters for the materials:
•The thermal conductivity, k
•The heat capacity, C
•The density, rho
•Young’s modulus, E
•Poisson’s ratio, nu
•The thermal expansion coefficient, alpha
and Tempereature

Regards,
Rashedul

2 Replies Last Post 2011年2月11日 GMT-5 09:16
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 2011年2月10日 GMT-5 15:20
Hi

COMSOL is different from many other FEM tools, these physical parameters are defined on the geometric "elements" and not into the mesh, the mesh elments are mapped on the domains and boundary , and the mesh heritate the physical properties from the domains respective boundaries.

So physical parameters are entered on the domains principally. Check the doc and test out the numerous examples, you will quickly learn.

By the way in V4 the GUI are rather different, you should consider if its worth to spend too much time on the older 3.5, rather from jumping straight into 4.1 or newer

--
Good luck
Ivar
Hi COMSOL is different from many other FEM tools, these physical parameters are defined on the geometric "elements" and not into the mesh, the mesh elments are mapped on the domains and boundary , and the mesh heritate the physical properties from the domains respective boundaries. So physical parameters are entered on the domains principally. Check the doc and test out the numerous examples, you will quickly learn. By the way in V4 the GUI are rather different, you should consider if its worth to spend too much time on the older 3.5, rather from jumping straight into 4.1 or newer -- Good luck Ivar

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Posted: 1 decade ago 2011年2月11日 GMT-5 09:16
Hi Ivar ,
Thanks for your reply. i was looking and learning some Model in Comsol library and it was

Model Library path: Structural_Mechanics_Module/Thermal-Structure_Interaction/microrobot_3d

in document, it was written,

PHYSICS SETTINGS
Because the microrobot legs consists of several materials with different material properties, you have to define subdomain settings for each materials. Using subdomain expression variables makes it easier to enter the subdomain properties of the model.
Define the following parameters for the materials:
•The thermal conductivity, k
•The heat capacity, C
•The density, rho
•Young’s modulus, E
•Poisson’s ratio, nu
•The thermal expansion coefficient, alpha
Also define a new variable, Temperature, to visualize the temperature in all domains in the postprocessing analysis.

Subdomain Expressions :

In comsol 3.5a, i couldn't find any place in option or Physics tool to define these parameters.


Thanks .

Hi Ivar , Thanks for your reply. i was looking and learning some Model in Comsol library and it was Model Library path: Structural_Mechanics_Module/Thermal-Structure_Interaction/microrobot_3d in document, it was written, PHYSICS SETTINGS Because the microrobot legs consists of several materials with different material properties, you have to define subdomain settings for each materials. Using subdomain expression variables makes it easier to enter the subdomain properties of the model. Define the following parameters for the materials: •The thermal conductivity, k •The heat capacity, C •The density, rho •Young’s modulus, E •Poisson’s ratio, nu •The thermal expansion coefficient, alpha Also define a new variable, Temperature, to visualize the temperature in all domains in the postprocessing analysis. Subdomain Expressions : In comsol 3.5a, i couldn't find any place in option or Physics tool to define these parameters. Thanks .

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