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.

question regarding meshing

Please login with a confirmed email address before reporting spam

Hi guys,

I'm new to simulation. And I got a question for a while: does the number of meshing elements significantly affect the simulation result? The reason I ask this is because that when the number of meshing elements is below a certain value, the simulation result doesn't make physical sense. However, once the number of meshing elements is beyond that certain value, the simulation result looks good. I don't know how to explain this. Any input is appreciated.

Cheers

2 Replies Last Post 10 giu 2011, 15:29 GMT-4
Jeff Hiller COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 10 giu 2011, 14:48 GMT-4
There are tons of Finite Element Analysis books out there that explain this in great detail, but in a nutshell it boils down to this:
Say I give you a wildly varying function f(x) defined over a segment [a;b] and I ask you to approximate it with a single straight line. The approximation won't be too good, right? Now, I ask you to approximate it with two straight lines, one over [a; (a+b)/2] and one over [(a+b)/2; b]. You'll be able to get a better approximation, but it still won't be very good, right? Now, continue this process: you're allowed 3 segments, then 4, then 5, etc. Your approximation will get better and better each time. With FEA, it's basically the same thing: the more degrees of freedom you have in a mesh, the closer you can approximate the actual solution of the PDEs that you're solving.
There are tons of Finite Element Analysis books out there that explain this in great detail, but in a nutshell it boils down to this: Say I give you a wildly varying function f(x) defined over a segment [a;b] and I ask you to approximate it with a single straight line. The approximation won't be too good, right? Now, I ask you to approximate it with two straight lines, one over [a; (a+b)/2] and one over [(a+b)/2; b]. You'll be able to get a better approximation, but it still won't be very good, right? Now, continue this process: you're allowed 3 segments, then 4, then 5, etc. Your approximation will get better and better each time. With FEA, it's basically the same thing: the more degrees of freedom you have in a mesh, the closer you can approximate the actual solution of the PDEs that you're solving.

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 10 giu 2011, 15:29 GMT-4

There are tons of Finite Element Analysis books out there that explain this in great detail, but in a nutshell it boils down to this:
Say I give you a wildly varying function f(x) defined over a segment [a;b] and I ask you to approximate it with a single straight line. The approximation won't be too good, right? Now, I ask you to approximate it with two straight lines, one over [a; (a+b)/2] and one over [(a+b)/2; b]. You'll be able to get a better approximation, but it still won't be very good, right? Now, continue this process: you're allowed 3 segments, then 4, then 5, etc. Your approximation will get better and better each time. With FEA, it's basically the same thing: the more degrees of freedom you have in a mesh, the closer you can approximate the actual solution of the PDEs that you're solving.


Thanks so much.
[QUOTE] There are tons of Finite Element Analysis books out there that explain this in great detail, but in a nutshell it boils down to this: Say I give you a wildly varying function f(x) defined over a segment [a;b] and I ask you to approximate it with a single straight line. The approximation won't be too good, right? Now, I ask you to approximate it with two straight lines, one over [a; (a+b)/2] and one over [(a+b)/2; b]. You'll be able to get a better approximation, but it still won't be very good, right? Now, continue this process: you're allowed 3 segments, then 4, then 5, etc. Your approximation will get better and better each time. With FEA, it's basically the same thing: the more degrees of freedom you have in a mesh, the closer you can approximate the actual solution of the PDEs that you're solving. [/QUOTE] Thanks so much.

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.