CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Meshing & Mesh Conversion

Meshing?

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   March 7, 2016, 07:52
Default Meshing?
  #1
New Member
 
Alpha Beta
Join Date: Mar 2016
Posts: 28
Rep Power: 2
xoitx is on a distinguished road
Is meshed area, the area within which the fluid will be flowing?
That is my understanding of mesh.. correct me if I'm wrong.
If so how do i include obstacles like a baffle plate.
I'm attempting to study sloshing in tanks (cylindrical)... any ideas?
I want to use gmsh or salome to do that so it's easier.. so how do I design the baffle plate?
Will it be a solid within a solid (using Boolean operation to delete mesh where baffle plate is supposed to be)? Cause I intend to get the stress values on the plates as well.
xoitx is offline   Reply With Quote

Old   March 7, 2016, 09:16
Default
  #2
Member
 
Alex
Join Date: Jan 2014
Posts: 94
Rep Power: 4
Kina is on a distinguished road
Quote:
Originally Posted by xoitx View Post
Is meshed area, the area within which the fluid will be flowing?
That is my understanding of mesh.. correct me if I'm wrong.
that's correct!

Quote:
Originally Posted by xoitx View Post
If so how do i include obstacles like a baffle plate.
those are the areas left out in the meshing, as you wrote with a boolean operation. only the fluid is meshed.

Quote:
Originally Posted by xoitx View Post
Cause I intend to get the stress values on the plates as well.
For this, you would have to implement an FSI (1 way should work). That way, you can project the pressure field of the CFD simulation onto a mechanical model of the baffle and let FEM calculate the stresses. Is that what you are trying to achieve?

Cheers
Alex
Kina is offline   Reply With Quote

Old   March 7, 2016, 12:10
Default
  #3
New Member
 
Alpha Beta
Join Date: Mar 2016
Posts: 28
Rep Power: 2
xoitx is on a distinguished road
What I'm trying to achieve is a simulation of what sloshing looks like without a baffle plate and also with a baffle plate but in various orientations/designs so as to get optimum effect.
My understanding so far is that I have to do the Boolean thing and get the effect without the actual model so that fluid is sloshing mid-air without any container :O .. then somehow add container later via blender or something... Is this right?
And after I get meshed entity.. how do I slosh it about? :P (I have to fill container to a certain percentage.. is there a variable for this? or do I have to keep meshing about?)
Any kind of help is appreciated
xoitx is offline   Reply With Quote

Old   March 7, 2016, 12:14
Default
  #4
New Member
 
Alpha Beta
Join Date: Mar 2016
Posts: 28
Rep Power: 2
xoitx is on a distinguished road
[QUOTE=Kina;588464
For this, you would have to implement an FSI (1 way should work). That way, you can project the pressure field of the CFD simulation onto a mechanical model of the baffle and let FEM calculate the stresses. Is that what you are trying to achieve?

Cheers
Alex[/QUOTE]

Pretty much .. but I'll do that later if I have time .. I could just run a simple stress analysis on the plate for now.
xoitx is offline   Reply With Quote

Old   March 8, 2016, 03:06
Default
  #5
Member
 
Alex
Join Date: Jan 2014
Posts: 94
Rep Power: 4
Kina is on a distinguished road
Quote:
Originally Posted by xoitx View Post
What I'm trying to achieve is a simulation of what sloshing looks like without a baffle plate and also with a baffle plate but in various orientations/designs so as to get optimum effect.
My understanding so far is that I have to do the Boolean thing and get the effect without the actual model so that fluid is sloshing mid-air without any container :O .. then somehow add container later via blender or something... Is this right?
And after I get meshed entity.. how do I slosh it about? :P (I have to fill container to a certain percentage.. is there a variable for this? or do I have to keep meshing about?)
Any kind of help is appreciated
I get a little confused with your terminology of 'stress". Do you mean forces or fluid pressure exerted on the baffle plate? In CFD, we don't explicitly design the solids around the fluid. In CFD, there is only fluid or not fluid. You would do "the Boolean thing" and define the face between the baffle plate and the fluid as "baffle wall" and then monitor the pressure and forces of this wall during the calculation.
I strongly recommend reading the damBreak tutorial. This will give you a first idea of what you might want to realize in terms of setup.
Kina is offline   Reply With Quote

Old   March 11, 2016, 10:48
Default Help!!
  #6
New Member
 
Alpha Beta
Join Date: Mar 2016
Posts: 28
Rep Power: 2
xoitx is on a distinguished road
Hi Kina
I successfully ran the SloshingTank3d tutorial in the interDymFoam folder
That is basically what I'm going for..
I tried to make a cylinder mesh with a boolean cut inside using salome.
I meshed it and then created a surface group for the whole thing as 'walls' , exported it as unv and used ideasUnvToFoam and setfields and finally interDymfoam.
The whole thing worked.
But I cant see the moving water inside.. Its just the empty cylinder with a boolean cut inside swaying. Can't I use 'boxtocell' inside a cylinder? How do I half fill the cylinder? I'm assuming it's something other than 'boxTocell' although I don't see how this is a problem.. It should just fall down and splash all over.. right?
And is the mesh right?
I meshed it in Salome and then created "surface" group and grouped it as 'walls'
In paraview it seemed wrong as only the surfaces were meshed.. there was no mesh inside the volume.
I tried meshing and grouping as "volume" but the setfields command returns an error.. I'm guessing this method is totally wrong
I don't know if its the mesh that's wrong or the setFieldsdict
Please do Help.
Thanks
xoitx is offline   Reply With Quote

Old   March 17, 2016, 14:48
Default
  #7
New Member
 
Alpha Beta
Join Date: Mar 2016
Posts: 28
Rep Power: 2
xoitx is on a distinguished road
Hot a better way.. toposetdict contains some useful info on setting up the water phase (alpha.water file).
I'm using
Quote:
regions
(
targetVolumeToCell // Fills volume below given plane
{
volume 7.86905;
normal (0 1 0); // usually in direction of gravity
fieldValues
(
volScalarFieldValue alpha.water 1
);
to half fill any structure.
In case anyone needed to know :P
xoitx is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
[ANSYS Meshing] only automatic meshing works, kazra ANSYS Meshing & Geometry 1 March 9, 2016 02:10
[ANSYS Meshing] Can I use ANSYS Meshing for manual meshing? Kirjain ANSYS Meshing & Geometry 6 November 30, 2015 09:11
[gmsh] Vertex numbering is dense KateEisenhower Open Source Meshers: Gmsh, Netgen, CGNS, ... 7 August 3, 2015 10:49
[ANSYS Meshing] Icem meshing queries Mfaizan ANSYS Meshing & Geometry 21 July 30, 2015 23:10
Singularity of grid?Volume meshing vs face meshing Ken Main CFD Forum 0 September 4, 2003 11:09


All times are GMT -4. The time now is 05:47.