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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 The information provided may be out of date.

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The affect of air flow on cantilever

Posted 2013年11月18日 GMT-5 14:39 MEMS & Nanotechnology, Fluid & Heat, MEMS & Piezoelectric Devices, Microfluidics, Geometry, Materials, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.0, Version 4.0a 3 Replies

Areen Allataifeh
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I'm working on a project on COMSOL to study the affect of flow on cantilever, I used laminar flow and solid mechanics in my model. I drew the cantilever with fixed end in a box.
two surfaces of the box have been identified as the inlet and the outlet of the flow.and the cantilever in the center of the box.

The error I'm getting is :

cannot evaluate expression
Failed to evaluate expression
Expression: mod1.spf.U
failed to evaluate variable.
variable: mod1.spf.U
- Geometry : 1
- Boundary : 9
- Plot: surf1 ( surface )

while boundary 9 in my model belongs to the cantilever( the fixed one )
Please, I need an urgent help desperately as the project should be submitted by Thursday.
I attached the model that I did.
Thanks a lot in advance

Attachments:

3 Replies Last Post 2013年11月22日 GMT-5 23:24
Areen Allataifeh
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Posted: 1 decade ago 2013年11月19日 GMT-5 13:26
I tried to change the model and now I'm getting a new error ... please reply, I desperately need some help

the error that I'm getting
There are 236 void equations (empty rows in matrix) for the variable mod1.w
at coordinates: (-0.00025,-0.00025,-0.00025), (-0.00025,-0.0002,-0.00025), (-0.00025,-0.000225,-0.00025), (-0.00025,-0.00025,-0.000225), (-0.00025,-0.00025,-0.0002), ...

also another error :
Variables not coupled to any dof
- Detail: mod1.solid.Tn p3

I attached to this comment the new model
I tried to change the model and now I'm getting a new error ... please reply, I desperately need some help the error that I'm getting There are 236 void equations (empty rows in matrix) for the variable mod1.w at coordinates: (-0.00025,-0.00025,-0.00025), (-0.00025,-0.0002,-0.00025), (-0.00025,-0.000225,-0.00025), (-0.00025,-0.00025,-0.000225), (-0.00025,-0.00025,-0.0002), ... also another error : Variables not coupled to any dof - Detail: mod1.solid.Tn p3 I attached to this comment the new model

Attachments:

Alex Lindjuk
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Posted: 1 decade ago 2013年11月22日 GMT-5 04:12
You have to many senseless contact pairs. Don't contact air domain with silicon domain. For your silicon domains use only bool operator union and not contact. And you have material error because you must define the domain 3 as silicon.
You have to many senseless contact pairs. Don't contact air domain with silicon domain. For your silicon domains use only bool operator union and not contact. And you have material error because you must define the domain 3 as silicon.
Areen Allataifeh
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Posted: 1 decade ago 2013年11月22日 GMT-5 23:24
thank you for your help :)
thank you for your help :)

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