Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.
Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
Different meshes for a multilayer
Posted 7 sept. 2012, 13:55 UTC−4 Geometry, Mesh Version 4.2a 6 Replies
Please login with a confirmed email address before reporting spam
Dear all,
I have to implement in Comsol a multilayer, that has a first layer (100x100x2 [mm]) with fillets and a second layer (140x140x3 [mm]) that is a uniform parallelepiped. To mesh the second layer I should use a "mapped mesh" in combination with "swept" function. On the other hand, for the first layer I may not use the mapped mesh but a "tetrahedral mesh", due to the complex shape.
Doing these meshes, I get an error from Comsol, because when I set "swept" in the "source faces" I have to insert two faces:
1) Is the face jointed with the first layer
2) Is the remaining area of the second layer, that is (140x140) - (100x100)
The error is I must insert only one source face and only one destination face (at least in my case).
I tried to bypass this problem using the lateral faces, so 140x3 as source and 140x3 as destination, but in this case the error is that I have another domain jointed to my domain.
-> How can I resolve this problem?
I specify I am using "Form union" instead of "Form assembly". Using "Form assembly", I don't get this error, but in the simulation only one layer seems to be deformed, the second is independent, it does not deform.
-> What you suggest me to set simulating a multilayer (no friction between layers, they are jointed)?
I wish I made myself clear. Thank you in advance.
Lucio
I have to implement in Comsol a multilayer, that has a first layer (100x100x2 [mm]) with fillets and a second layer (140x140x3 [mm]) that is a uniform parallelepiped. To mesh the second layer I should use a "mapped mesh" in combination with "swept" function. On the other hand, for the first layer I may not use the mapped mesh but a "tetrahedral mesh", due to the complex shape.
Doing these meshes, I get an error from Comsol, because when I set "swept" in the "source faces" I have to insert two faces:
1) Is the face jointed with the first layer
2) Is the remaining area of the second layer, that is (140x140) - (100x100)
The error is I must insert only one source face and only one destination face (at least in my case).
I tried to bypass this problem using the lateral faces, so 140x3 as source and 140x3 as destination, but in this case the error is that I have another domain jointed to my domain.
-> How can I resolve this problem?
I specify I am using "Form union" instead of "Form assembly". Using "Form assembly", I don't get this error, but in the simulation only one layer seems to be deformed, the second is independent, it does not deform.
-> What you suggest me to set simulating a multilayer (no friction between layers, they are jointed)?
I wish I made myself clear. Thank you in advance.
Lucio
6 Replies Last Post 9 sept. 2012, 17:46 UTC−4
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi
there are a few limitations with the mapped mesh, if you have rectangles, the easiest is to cut them such that they have common borders on all sides, that is if you have a 140x140x3 block in contact with the 100x100x2 over the 100x100 mm common area, then cut your model into "rectangles such that the 140x140x3 is split into a 100x100x3 matchin the 100x100x2 and then some others on the side. Then you should be able to sweep mesh the larger union of blocks, then you must "convert" the mesh on the common boundary to thets, and you can mesh the 100x100x2 in thets
All this in Union Mode, in Assembly mode, whcich is also possible you do not ned to split up your large block, but you must then manually look after all (in your case 1?) common identity boundaries, and you must enshure your mesh is dense enogh to transfer well the flux of whatever traverses your common boundary.
Hope I got it clear enough ;)
--
Good luck
Ivar
there are a few limitations with the mapped mesh, if you have rectangles, the easiest is to cut them such that they have common borders on all sides, that is if you have a 140x140x3 block in contact with the 100x100x2 over the 100x100 mm common area, then cut your model into "rectangles such that the 140x140x3 is split into a 100x100x3 matchin the 100x100x2 and then some others on the side. Then you should be able to sweep mesh the larger union of blocks, then you must "convert" the mesh on the common boundary to thets, and you can mesh the 100x100x2 in thets
All this in Union Mode, in Assembly mode, whcich is also possible you do not ned to split up your large block, but you must then manually look after all (in your case 1?) common identity boundaries, and you must enshure your mesh is dense enogh to transfer well the flux of whatever traverses your common boundary.
Hope I got it clear enough ;)
--
Good luck
Ivar
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi Ivar,
Thank you very much for your useful suggestion. Unfortunately the fillets are between the edge 100x2 (sorry, I didn't specify that), i.e. the contacting area on the 140x140 layer is a square with fillets (unable to be meshed by mapped mesh). Nonetheless, your suggestion will be useful for other models.
Therefore, I would use the assembly mode. First of all, how should I set the options in the "Finalize" node? I have consulted the guides of Comsol about the difference of Union and Assembly, but it is not very clear, in addition I cannot understand the difference between Create Pairs and Create Imprints.
Have I to set further options when I use the Assembly mode?
If you consider I'm going off topic, I will open a new discussion or I could continue another one.
Regards
Thank you very much for your useful suggestion. Unfortunately the fillets are between the edge 100x2 (sorry, I didn't specify that), i.e. the contacting area on the 140x140 layer is a square with fillets (unable to be meshed by mapped mesh). Nonetheless, your suggestion will be useful for other models.
Therefore, I would use the assembly mode. First of all, how should I set the options in the "Finalize" node? I have consulted the guides of Comsol about the difference of Union and Assembly, but it is not very clear, in addition I cannot understand the difference between Create Pairs and Create Imprints.
Have I to set further options when I use the Assembly mode?
If you consider I'm going off topic, I will open a new discussion or I could continue another one.
Regards
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi
check the forum (search) there are several discussion about union and assembl.
in a few words union creates common "continuation" boundaries for all domains in (adjacent) contact
while assembly creates double ouverlapping boundaries (one per domain), and its up to you manually to create identty pairs and define ALL physics contiunation pair groups
Imprints means that overlapping boundaries but of different sizes for their respective domains, are cut up in segments so their length matches. This is cetainly a must for your case.
You need identity pairs and not contact pairs, except if you want your boundaries to separate (hence no continuum)
If you have several domains, but you only want dedoubled boundaries for 2 of these, then group the domains with an Explicit UNION in the graphics node, then your assembly mode will only operate between the unions or the single domain and the union, this reduces the number of pair to treat, (all boundary within an union will be unique and respect flux continuation across them
COMSOL assembly has nothing to do with the notion of classical CAD assembly of multiple parts, do not mix up ;)
--
Good luck
Ivar
check the forum (search) there are several discussion about union and assembl.
in a few words union creates common "continuation" boundaries for all domains in (adjacent) contact
while assembly creates double ouverlapping boundaries (one per domain), and its up to you manually to create identty pairs and define ALL physics contiunation pair groups
Imprints means that overlapping boundaries but of different sizes for their respective domains, are cut up in segments so their length matches. This is cetainly a must for your case.
You need identity pairs and not contact pairs, except if you want your boundaries to separate (hence no continuum)
If you have several domains, but you only want dedoubled boundaries for 2 of these, then group the domains with an Explicit UNION in the graphics node, then your assembly mode will only operate between the unions or the single domain and the union, this reduces the number of pair to treat, (all boundary within an union will be unique and respect flux continuation across them
COMSOL assembly has nothing to do with the notion of classical CAD assembly of multiple parts, do not mix up ;)
--
Good luck
Ivar
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi Ivar,
I am not still able to work my model out, using the Assembly mode.
Considering a simple model, that is two beam connected (such as a multilayer). The extremities of these beams are fixed, and the opposite extremities are free.
Only the upper beam is at high temperature.
In fig.1 as attached you can see how I set the assembly mode and the Identity Pair (4 and 9 are the two faces in contact) and in fig.Displ you can see my result: It is obvious that is wrong, only the upper beam deformed.
Notes that:
In this case I could have used only mapped meshes, but we can assume we want a tetrahedral mesh on the upper beam.
I am not using "Imprints" in the Finalize node otherwise I saw it is not possible to use the mapped mesh (I will have 3 faces of destination, not 1 face). Practically, the same problem using Union mode.
Where am I doing wrong with Assembly?
Thank you again
Lucio F.
I am not still able to work my model out, using the Assembly mode.
Considering a simple model, that is two beam connected (such as a multilayer). The extremities of these beams are fixed, and the opposite extremities are free.
Only the upper beam is at high temperature.
In fig.1 as attached you can see how I set the assembly mode and the Identity Pair (4 and 9 are the two faces in contact) and in fig.Displ you can see my result: It is obvious that is wrong, only the upper beam deformed.
Notes that:
In this case I could have used only mapped meshes, but we can assume we want a tetrahedral mesh on the upper beam.
I am not using "Imprints" in the Finalize node otherwise I saw it is not possible to use the mapped mesh (I will have 3 faces of destination, not 1 face). Practically, the same problem using Union mode.
Where am I doing wrong with Assembly?
Thank you again
Lucio F.
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi
did you add a node : Solid - Boundary - Pair - continuity and selected the identity pair ? I bet not ... hence no continuity ...
--
Good luck
Ivar
did you add a node : Solid - Boundary - Pair - continuity and selected the identity pair ? I bet not ... hence no continuity ...
--
Good luck
Ivar
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi Ivar,
You're right! I didn't know the setting of this node. Now everything works correctly
Thank you very much indeed!
Lucio
You're right! I didn't know the setting of this node. Now everything works correctly
Thank you very much indeed!
Lucio