CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT

simulation of free surface of stirred tank using vof

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

Like Tree6Likes

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   November 23, 2012, 03:35
Default simulation of free surface of stirred tank using vof
  #1
Senior Member
 
Jamal Foroozesh
Join Date: Oct 2012
Location: Iran
Posts: 162
Rep Power: 13
jamalf64 is on a distinguished road
Hi alls,
I want to simulate free surface of stirred tank.
I've solved my problem but it seems that results are wrong.
System should be stable after a period of time, but did not stable.
I think thak I don’t do a part of problem.
What should I do that I have not done?
Step by step of my problem:
Read msh file
1) Make grid interfaces (rotor-stator interface)
2) Set multiphase model to VOF with default parameters
3) Set K-E with default parameters
4) Copy water-liquid from materials database
5) Define Air as primary phase
6) Define water as secondary phase
7) Operating condition: active gravity and set -9.81 to Z, (0 0 26.5) as reference pressure location
8) Boundary condition:
A) Rotor fluid: whether moving mesh or mrf , 200rpm
B) Rest fluid: stationary
C) Impeller: stationary
D) Shaft: absolute rotational, 200rpm
E) Top of tank: symmetry
F) Tank walls: no slip
10) initialize, init with default parameters
11) Adapt/ region/ (Xmin=-12, Xmax=12) (Ymin=-12, Ymac=12) (Zmin=0, Zmax=21.5)/ mark
12) initialize/ patch/ volume fraction of water in marked zone is set to 1
13) all parameters of solution is default of fluent
14) time step=0.001 or 0.0001
15) iterate
Attached Images
File Type: png stirred tank.png (28.7 KB, 63 views)
File Type: jpg 1.jpg (97.7 KB, 75 views)
File Type: png impeller_2.PNG (34.9 KB, 56 views)
jamalf64 is offline   Reply With Quote

Old   November 23, 2012, 05:18
Default
  #2
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 3,297
Rep Power: 41
-mAx- will become famous soon enough
pictures of your weird results?
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is offline   Reply With Quote

Old   November 23, 2012, 06:01
Default
  #3
Senior Member
 
Jamal Foroozesh
Join Date: Oct 2012
Location: Iran
Posts: 162
Rep Power: 13
jamalf64 is on a distinguished road
Quote:
Originally Posted by -mAx- View Post
pictures of your weird results?
they are here: http://www.cfd-online.com/Forums/flu...tml#post393765
jamalf64 is offline   Reply With Quote

Old   November 23, 2012, 06:07
Default
  #4
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 3,297
Rep Power: 41
-mAx- will become famous soon enough
i would say interfaces issue -- are those spots exactly where interfaces-intersection are ?
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is offline   Reply With Quote

Old   November 23, 2012, 06:13
Default
  #5
Senior Member
 
Jamal Foroozesh
Join Date: Oct 2012
Location: Iran
Posts: 162
Rep Power: 13
jamalf64 is on a distinguished road
Quote:
Originally Posted by -mAx- View Post
i would say interfaces issue -- are those spots exactly where interfaces-intersection are ?
which spots?
jamalf64 is offline   Reply With Quote

Old   November 23, 2012, 06:21
Default
  #6
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 3,297
Rep Power: 41
-mAx- will become famous soon enough
the four red you see on each picture...
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is offline   Reply With Quote

Old   November 23, 2012, 06:27
Default
  #7
Senior Member
 
Jamal Foroozesh
Join Date: Oct 2012
Location: Iran
Posts: 162
Rep Power: 13
jamalf64 is on a distinguished road
Quote:
Originally Posted by -mAx- View Post
the four red you see on each picture...
yes, spots and interfaces are overlap.
jamalf64 is offline   Reply With Quote

Old   November 23, 2012, 07:02
Default
  #8
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 3,297
Rep Power: 41
-mAx- will become famous soon enough
then here is the issue.
how many interfaces did you define?
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is offline   Reply With Quote

Old   November 23, 2012, 07:15
Default
  #9
Senior Member
 
Jamal Foroozesh
Join Date: Oct 2012
Location: Iran
Posts: 162
Rep Power: 13
jamalf64 is on a distinguished road
Quote:
Originally Posted by -mAx- View Post
then here is the issue.
how many interfaces did you define?
two interface, 1)rotor perimeter 2) part of rest tank that contact with rotor (You said to me earlier )
http://www.cfd-online.com/Forums/ans...nk-gambit.html
jamalf64 is offline   Reply With Quote

Old   November 23, 2012, 07:19
Default
  #10
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 3,297
Rep Power: 41
-mAx- will become famous soon enough
I would say 3:
*rotor perimeter
*top cap of rotor
*bottom cap of rotor
No?
Anyway are you dealing with moving mesh? if yes is it moving properly?
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is offline   Reply With Quote

Old   November 23, 2012, 07:26
Default
  #11
Senior Member
 
Jamal Foroozesh
Join Date: Oct 2012
Location: Iran
Posts: 162
Rep Power: 13
jamalf64 is on a distinguished road
Quote:
Originally Posted by -mAx- View Post
I would say 3:
*rotor perimeter
*top cap of rotor
*bottom cap of rotor
No?
Anyway are you dealing with moving mesh? if yes is it moving properly?
Exactly, I've done all these things and moving is proper
jamalf64 is offline   Reply With Quote

Old   November 23, 2012, 07:44
Default
  #12
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 3,297
Rep Power: 41
-mAx- will become famous soon enough
Quote:
Originally Posted by jamalf64 View Post
Exactly, I've done all these things and moving is proper
Quote:
Originally Posted by jamalf64 View Post
two interface, 1)rotor perimeter 2) part of rest tank that contact with rotor
So 2 or 3 interfaces defined in Fluent?
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is offline   Reply With Quote

Old   November 23, 2012, 07:56
Default
  #13
Senior Member
 
Jamal Foroozesh
Join Date: Oct 2012
Location: Iran
Posts: 162
Rep Power: 13
jamalf64 is on a distinguished road
Quote:
Originally Posted by -mAx- View Post
So 2 or 3 interfaces defined in Fluent?
I defined rotor perimeter, top cap of rotor, bottom cap of rotor as one interface in GAMBIT and every three are defined rotor interface(as one interface) in fluent
Stator interface is defined similar to rotor
jamalf64 is offline   Reply With Quote

Old   November 23, 2012, 08:02
Default
  #14
Super Moderator
 
-mAx-'s Avatar
 
Maxime Perelli
Join Date: Mar 2009
Location: Switzerland
Posts: 3,297
Rep Power: 41
-mAx- will become famous soon enough
Quote:
Originally Posted by jamalf64 View Post
I defined rotor perimeter, top cap of rotor, bottom cap of rotor as one interface in GAMBIT and every three are defined rotor interface(as one interface) in fluent
It is not correct in regards of topology, because for one interface all surfaces should slide on each other

defined in gambit:
top cap rotor as interface 1
top cap stator as interface 2
bottom cap rotor as interface 3
bottom cap stator as interface 4
perimeter rotor as interface 5
perimeter stator as interface 6

Then in fluent:
grid interface A using interfaces 1 & 2
grid interface B using interfaces 3 & 4
grid interface C using interfaces 5 & 6
__________________
In memory of my friend Hervé: CFD engineer & freerider
-mAx- is offline   Reply With Quote

Old   November 23, 2012, 08:07
Default
  #15
Senior Member
 
Jamal Foroozesh
Join Date: Oct 2012
Location: Iran
Posts: 162
Rep Power: 13
jamalf64 is on a distinguished road
Quote:
Originally Posted by -mAx- View Post
It is not correct in regards of topology, because for one interface all surfaces should slide on each other

defined in gambit:
top cap rotor as interface 1
top cap stator as interface 2
bottom cap rotor as interface 3
bottom cap stator as interface 4
perimeter rotor as interface 5
perimeter stator as interface 6

Then in fluent:
grid interface A using interfaces 1 & 2
grid interface B using interfaces 3 & 4
grid interface C using interfaces 5 & 6
Thank you so much
I'll do the things you said and report the results to you
jamalf64 is offline   Reply With Quote

Old   November 23, 2012, 09:26
Default
  #16
Senior Member
 
ghost82's Avatar
 
Rick
Join Date: Oct 2010
Posts: 1,016
Rep Power: 26
ghost82 will become famous soon enough
Jamal,
also, if you use mrf you don't need any interface!Create interfaces, as explained by max, only if you use sliding mesh.
If you use mrf you have only to define 2 fluid zones (rotor and stator), without interfaces.

EDIT: "if you use mrf you don't need any interface!" --> if you have a conformal mesh

Last edited by ghost82; November 23, 2012 at 09:46.
ghost82 is offline   Reply With Quote

Old   November 23, 2012, 09:40
Default
  #17
Far
Super Moderator
 
Sijal
Join Date: Mar 2009
Location: Islamabad
Posts: 4,553
Blog Entries: 6
Rep Power: 54
Far has a spectacular aura aboutFar has a spectacular aura about
Send a message via Skype™ to Far
Quote:
Originally Posted by ghost82 View Post
Jamal,
also, if you use mrf you don't need any interface!Create interfaces, as explained by max, only if you use sliding mesh.
If you use mrf you have only to define 2 fluid zones (rotor and stator), without interfaces.
What if the mesh is not conformal? Whether it is mrf or sliding mesh, interfaces should be defined as mrf can be thought as a special case of sliding mesh.
Far is offline   Reply With Quote

Old   November 23, 2012, 09:45
Default
  #18
Senior Member
 
ghost82's Avatar
 
Rick
Join Date: Oct 2010
Posts: 1,016
Rep Power: 26
ghost82 will become famous soon enough
Quote:
Originally Posted by Far View Post
What if the mesh is not conformal? Whether it is mrf or sliding mesh, interfaces should be defined as mrf can be thought as a special case of sliding mesh.
Yes Far, if you have a non conformal mesh, then interfaces are necessary also for mrf; however, in my cases, if I used mrf, I preferred to not create interfaces, as in post processing some discontinuities may appear on non conformal interfaces, between fluid zones.

Looking at the mesh model, I think it is quite simple to not create interfaces.

Daniele
ghost82 is offline   Reply With Quote

Old   November 23, 2012, 09:55
Default
  #19
Far
Super Moderator
 
Sijal
Join Date: Mar 2009
Location: Islamabad
Posts: 4,553
Blog Entries: 6
Rep Power: 54
Far has a spectacular aura aboutFar has a spectacular aura about
Send a message via Skype™ to Far
Quote:
Originally Posted by ghost82 View Post
Yes Far, if you have a non conformal mesh, then interfaces are necessary also for mrf; however, in my cases, if I used mrf, I preferred to not create interfaces, as in post processing some discontinuities may appear on non conformal interfaces, between fluid zones.

Looking at the mesh model, I think it is quite simple to not create interfaces.

Daniele

I agree..... Thats perfect
Far is offline   Reply With Quote

Old   November 23, 2012, 09:57
Default
  #20
Senior Member
 
Jamal Foroozesh
Join Date: Oct 2012
Location: Iran
Posts: 162
Rep Power: 13
jamalf64 is on a distinguished road
Thanks all to your responses
jamalf64 is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
VOF in free surface alilouu FLUENT 0 September 27, 2011 07:32
VOF and Free surface model...are they same? Kushagra CFX 1 November 14, 2008 13:36
Can I have solid in the free surface simulation? ggbaby Siemens 0 September 5, 2006 06:45
Free surface of Step with VOF Azin Sharafeddin FLUENT 1 May 26, 2004 06:24
free convection heat transfer from a heated horizontal surface through a liquid to a thin cooled fin Kaushik FLUENT 1 May 8, 2000 07:47


All times are GMT -4. The time now is 06:24.