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 The information provided may be out of date.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.
Laminar flow, solid mechanics, moving mesh! Dear Comsol engineers, can some one give me some suggestions?
Posted Apr 8, 2011, 2:27 p.m. EDT Version 3.5a, Version 4.1 4 Replies
Please login with a confirmed email address before reporting spam
Dear Mr. Ivar or some other nice persons,
I did my single vein valve with laminar, solid mechanics and moving mesh in V.4.1a, and when I try to run it, it just keeping showing error:
Compile Equations
error expression
Actually my senior lab-mate has done almost the same model which is double valve in the version 3.5, my professor ask me to do it in the Version 4.1(before I go further modeling some more complicated models), but I am really so weak at Comsol ?although I already learn it for almost 4 months), can someone help me to fix it ? I would be so appreciated!
Attached is the 3.5 version and my 4.1 version! But the 3.5 version is too big to attached! Is there anyway I can attach it?
I did my single vein valve with laminar, solid mechanics and moving mesh in V.4.1a, and when I try to run it, it just keeping showing error:
Compile Equations
error expression
Actually my senior lab-mate has done almost the same model which is double valve in the version 3.5, my professor ask me to do it in the Version 4.1(before I go further modeling some more complicated models), but I am really so weak at Comsol ?although I already learn it for almost 4 months), can someone help me to fix it ? I would be so appreciated!
Attached is the 3.5 version and my 4.1 version! But the 3.5 version is too big to attached! Is there anyway I can attach it?
Attachments:
4 Replies Last Post Apr 9, 2011, 11:29 a.m. EDT
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi
there are many things here that I do not really catch, but I believe also it's because I do not fully understand your model, a few items I can suggest to check:
1) you could probably use the FSI module, as there all three physics are already combined
2) the inlet 1 you set up the velocity with an "s" but you have 3 segments, and s is redefined on each going from 0, to 1 along the edge, have you checked that the initial value velocity is already more or less as expected ?
3) I do not understand "inlet 2" this is a wall not an inlet ? I'm missing something ;)
4) boundary loads 1 and 3 of "0" do not bring anything
5) in the solid Mechanics do not leave an entry empty, add a "0" to the xref (even if you do not use it)
6) in the moving mesh, by default everything is fixed, I believe you should set a free deformation to the fluid part
7) your prescribed mesh displacement is not set you need to define something also for the boundaries
8) remove the not used solver cases and keep only one
9) try to solve only one physics at the time, to check that they are ok, you can also just get the initial conditions loaded to test those also
I still need to understand what you are doing with your set of weak constraints, but that is just that I need to go through the equations, these might be perfectly OK
Still not enough to get it solving.
Again these are comments I would have done differently, not necessarily errors, as your model looks rather complex and I do not believe I fully understand it ;)
--
Good luck
Ivar
there are many things here that I do not really catch, but I believe also it's because I do not fully understand your model, a few items I can suggest to check:
1) you could probably use the FSI module, as there all three physics are already combined
2) the inlet 1 you set up the velocity with an "s" but you have 3 segments, and s is redefined on each going from 0, to 1 along the edge, have you checked that the initial value velocity is already more or less as expected ?
3) I do not understand "inlet 2" this is a wall not an inlet ? I'm missing something ;)
4) boundary loads 1 and 3 of "0" do not bring anything
5) in the solid Mechanics do not leave an entry empty, add a "0" to the xref (even if you do not use it)
6) in the moving mesh, by default everything is fixed, I believe you should set a free deformation to the fluid part
7) your prescribed mesh displacement is not set you need to define something also for the boundaries
8) remove the not used solver cases and keep only one
9) try to solve only one physics at the time, to check that they are ok, you can also just get the initial conditions loaded to test those also
I still need to understand what you are doing with your set of weak constraints, but that is just that I need to go through the equations, these might be perfectly OK
Still not enough to get it solving.
Again these are comments I would have done differently, not necessarily errors, as your model looks rather complex and I do not believe I fully understand it ;)
--
Good luck
Ivar
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Thank you so much!
Actually I have this model which is done in version 3.5a by my senior labmates, but I cannot attached it, it is too big!
Do you know someplace I can upload it for you to check it, I really don't know what should I do with it?
It is just the new version is really different from the old one!
Thank you, Mr. Ivar. You are so ice, I will try to do it as you said!
Actually I have this model which is done in version 3.5a by my senior labmates, but I cannot attached it, it is too big!
Do you know someplace I can upload it for you to check it, I really don't know what should I do with it?
It is just the new version is really different from the old one!
Thank you, Mr. Ivar. You are so ice, I will try to do it as you said!
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi
indeed there are quite some differences, I'm trying to forget all about 3.5 to not get confused, I would say it's better to concentrate on the new (latest) v4
You can always in 3.5 as in v4:
"reset" the model, in v3.5 it also deletes the mesh that might be a hassle as it can be difficult to regenerate, what is no problem any longer in v4.
You can always do a "solve for initial conditions" in v3.5 then the full solution is lost, but the model file shrinks also significantly, before an upload. Sometimes in older version a zip can also help, in the new v4 its already zipped up
--
Good luck
Ivar
indeed there are quite some differences, I'm trying to forget all about 3.5 to not get confused, I would say it's better to concentrate on the new (latest) v4
You can always in 3.5 as in v4:
"reset" the model, in v3.5 it also deletes the mesh that might be a hassle as it can be difficult to regenerate, what is no problem any longer in v4.
You can always do a "solve for initial conditions" in v3.5 then the full solution is lost, but the model file shrinks also significantly, before an upload. Sometimes in older version a zip can also help, in the new v4 its already zipped up
--
Good luck
Ivar
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Sorry for the confusion of my model, I will draw a graph in paper which can describe my model clearly before next time you can check my model for me?
Thank you so much again!
Thank you so much again!