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.

meshing thin structures

Please login with a confirmed email address before reporting spam

hi

i have a mesh of heat pipe with dimension 1 m longe (y) and 0.012 m (x) with, the mesh generation has been dificultous.

i want to know , how it solution the problema

i read the manual comsol about scale, but for my problem how is the scale?

thanks for attention


6 Replies Last Post 2012年5月26日 GMT-4 09:36
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 2012年4月9日 GMT-4 13:10
Hi

are you in 2D, or 2D axi or ... ? you can also, if the default meshing does not give you what you want, start to mesh a boundary and sweep it over the domain(s)

--
Good luck
Ivar
Hi are you in 2D, or 2D axi or ... ? you can also, if the default meshing does not give you what you want, start to mesh a boundary and sweep it over the domain(s) -- Good luck Ivar

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 2012年4月9日 GMT-4 13:28
It's hard to tell as you don't provide enough details about your structure. But generally, you can mesh the short edge and then sweep along the long one. Also for thin layers square mesh usually works better than triangular
It's hard to tell as you don't provide enough details about your structure. But generally, you can mesh the short edge and then sweep along the long one. Also for thin layers square mesh usually works better than triangular

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 2012年4月10日 GMT-4 12:23
hi

my mesh is 2D, but i want to know the scale geometry with dimensions 1m (longe) y and 0.017 m (witdth).
this dimensions are a quad
hi my mesh is 2D, but i want to know the scale geometry with dimensions 1m (longe) y and 0.017 m (witdth). this dimensions are a quad

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 2012年4月10日 GMT-4 13:43
Hi

I havent used 3.5 for a very long time, but if you have a rectangle 1m in X and 17 mm in Y then if you mesh it by default you will certainly get one element height (along Y) and a few dozen along the 1m length. There is somewhere an option to scale/stretch the geometry, you can use a factor 50 for Y, then your geometry will be virtually expanded 50 times, you will see the mesher make a more or less regular mesh, and then it will contract the result 50 time along Y. The result is a very low quality mesh per say, but could certainly be OK to catch steep gradient along Y.

But if your geoemtry is a rectangle, you can as well add a dimension along the two short Y dges and mesh first these adges with say 25-50 elements, and then add a quad on the domain you will get the same result.

Another way to get a fine mesh along an edge where you have a large gradient (time solveing HT cases) is to use a boundary mesh, check the doc

--
Good luck
Ivar
Hi I havent used 3.5 for a very long time, but if you have a rectangle 1m in X and 17 mm in Y then if you mesh it by default you will certainly get one element height (along Y) and a few dozen along the 1m length. There is somewhere an option to scale/stretch the geometry, you can use a factor 50 for Y, then your geometry will be virtually expanded 50 times, you will see the mesher make a more or less regular mesh, and then it will contract the result 50 time along Y. The result is a very low quality mesh per say, but could certainly be OK to catch steep gradient along Y. But if your geoemtry is a rectangle, you can as well add a dimension along the two short Y dges and mesh first these adges with say 25-50 elements, and then add a quad on the domain you will get the same result. Another way to get a fine mesh along an edge where you have a large gradient (time solveing HT cases) is to use a boundary mesh, check the doc -- Good luck Ivar

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 2012年5月26日 GMT-4 09:27
hello, i have problem

i having a simulation of heat pipe high temperature

after, i run my simulation and result a expresion " undefined value comand ", there are 141 gradees of freedown . giving NaN/ inf. in the vector of variable w sodio.

i can not understand this



Thanks for attention
hello, i have problem i having a simulation of heat pipe high temperature after, i run my simulation and result a expresion " undefined value comand ", there are 141 gradees of freedown . giving NaN/ inf. in the vector of variable w sodio. i can not understand this Thanks for attention

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 2012年5月26日 GMT-4 09:36
Hi

that mostly means there are not enough BCs to give an unique solution, recheck carefully your model to see if all physics and dependent variables have enough boundary settings

--
Good luck
Ivar
Hi that mostly means there are not enough BCs to give an unique solution, recheck carefully your model to see if all physics and dependent variables have enough boundary settings -- Good luck Ivar

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.