Discussion Forum

Amey-

For thin structures, it is recommended to use mapped and/or swept meshing for these features. The free operations will give a less efficient mesh (if you happen to get no errors) as it seems you've noticed.

Best regards,
Josh Thomas
AltaSim Technologies

Hi,
i am trying to use a physics induced mesh for the entire structure. But,after meshing i'm getting the following error and i'm struck badly in overcoming this.
The error is; 'Edge is much shorter than specified minimum element size and Face is much shorter than minimum specified element size'.
Please help me.

Amey-

The message you described is not actually a fatal error, just a warning. However, if you'd like to clear out the warning, simply define a user-controlled mesh and reduce the minimum element size parameter.

Best regards,
Josh Thomas
AltaSim Technologies

Hi Josh,

what if i cant use swept or mapped mesh?(thin layers curved and tapered) because of their limitations?
i have thin layer(thickness=0.101mm).

Fnu-

Well, apart from just using the free tetrahedral mesher:

1) You can try using the "Form Assembly" option when you finalize your Geometry. This will enable you to mesh your domains independently which may cut down on total degrees of freedom as well as enable you to mesh without errors. The cost here is that you have to define identity pairs where the boundaries touch between the different domains. This may cause other solving difficulties as well.

2) Depending on the physics of your problem, you can consider approximating the behavior of your thin 3D layers using boundary (2D) equations. This is only if important variables don't change much across the thickness of your problem.

Best regards,
Josh Thomas
AltaSim Technologies

hi,
how much element size parameter i need to keep? that's the big problem,i have build my structure by rectangular domains on top of each other as if it would like front view of an fabricated switch model. I can do Modal analysis but fail in stationary analysis..i don't get beam displacement properly.
I used mapping meshing but error is, 'failed to create discretization of edge 6'. moreover when i do physics induced mesh i get warning,'face and edges are much smaller that specified minimum element size'.
kindly help,
Regards

Hi Josh,
thanks for the reply

my physics is piezoelectric devices, i guess i cant use identical pair assembly approach.
I have attached my model file(v4.3b), if its possible for you to have a look and give some suggestions(meshing),it will be very helpful.

many thanks.
mohammed.

Fnu-

It looks like you need to first consider that your geometry is not being created as you might anticipate. Your 2 imported files are not being unioned properly on the finalize node. I'd recommend performing the geometry Boolean operation in your native CAD package.

Also, have you considered by suggestion 2) above? You may consider not meshing in the thickness and instead using 2D boundary equations defined on the surfaces of the airfoil. I'm not an expert in the physics but it is worth considering.

Best regards,
Josh

Hi Josh,
thanks for reply.

i will try to re-import with Boolean geometry.

Also when you said '2D boundary equation defined on airfoil surface' can you name a example of that kind?
so that i can go through and try to implement on my model. coz if i can use that approach i can save lot of computation time and space.

many thanks.
mohammed.

Fnu-

This video gives an overview of how a film boiling layer was approximated using 2D equations.

www.comsol.com/video/heat-transfer-oil-quench-simulation

Regards,
Josh Thomas
AltaSim Technologies