CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Running, Solving & CFD

Circular miniFlume experimental amp numerical results

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

Reply
 
LinkBack Thread Tools Display Modes
Old   July 27, 2005, 11:56
Default Hi, I have many experimental
  #1
New Member
 
Amelia
Join Date: Mar 2009
Posts: 17
Rep Power: 8
amelia is on a distinguished road
Hi,
I have many experimental results obtained using the LDA technique, inside a small annular flume (see file attached). The fluid movement is provided by a lid, at the top of the mini flume. Although the gap between the bottom wall and the lid is 49 mm, measurements were made only up to 26 mm above the bottom.
Now, I am using Open FOAM, trying to find the best model for my case. The experimental tests were made at both laminar and turbulent Re; the fluid was an aqueous solution of glycerin (dynamic viscosity=3e-3 Pa.s and density=1076kg/m3). I send attached the results obtained experimentally (uz_exp.) and numerically (uz_num.), for the angular velocity of 41,89 rad/s. The numerical results were obtained using simpleFOAM and the k-e turbulence model considering the default values. Comparing the experimental and numerical results, it is possible to observe that profiles (Ux, Uy, Uz) are similar in form, however the magnitudes are quite different.
I am trying to justify that difference, thus I would like to know if I am using the correct model and if there are important factors inside the flume that are not being considered in the equations, such as centrifugal forces, since the experimental results show that the flow is pushed to the outer wall.


amelia is offline   Reply With Quote

Old   July 27, 2005, 12:00
Default
  #2
New Member
 
Amelia
Join Date: Mar 2009
Posts: 17
Rep Power: 8
amelia is on a distinguished road

amelia is offline   Reply With Quote

Old   July 27, 2005, 12:04
Default http://www.cfd-online.com/Open
  #3
New Member
 
Amelia
Join Date: Mar 2009
Posts: 17
Rep Power: 8
amelia is on a distinguished road

amelia is offline   Reply With Quote

Old   July 27, 2005, 12:05
Default http://www.cfd-online.com/Open
  #4
New Member
 
Amelia
Join Date: Mar 2009
Posts: 17
Rep Power: 8
amelia is on a distinguished road

amelia is offline   Reply With Quote

Old   July 27, 2005, 12:07
Default Circular miniFlume: http://
  #5
New Member
 
Amelia
Join Date: Mar 2009
Posts: 17
Rep Power: 8
amelia is on a distinguished road
Circular miniFlume:


amelia is offline   Reply With Quote

Old   August 31, 2005, 16:21
Default Hello, I modeled this geome
  #6
Senior Member
 
Billy
Join Date: Mar 2009
Posts: 167
Rep Power: 8
billy is on a distinguished road
Hello,

I modeled this geometry in 3D and obtained the above results.

Now, I modeled this geometry as an axi-symmetric geometry using wedge patch type. Actually, since the geometry has an inner diameter the block is not a wedge but a hexahedron. Then I defined two patches with wedge type. Is this the correct thing to do?
billy is offline   Reply With Quote

Old   August 31, 2005, 16:23
Default Hello, I modeled this geome
  #7
New Member
 
Amelia
Join Date: Mar 2009
Posts: 17
Rep Power: 8
amelia is on a distinguished road
Hello,

I modeled this geometry in 3D and obtained the above results.

Now, I modeled this geometry as an axi-symmetric geometry using wedge patch type. Actually, since the geometry has an inner diameter the block is not a wedge but a hexahedron. Then I defined two patches with wedge type. Is this the correct thing to do?
amelia is offline   Reply With Quote

Old   August 31, 2005, 16:28
Default It's still a wedge desite it n
  #8
Senior Member
 
Join Date: Mar 2009
Posts: 854
Rep Power: 13
henry is on a distinguished road
It's still a wedge desite it not reaching the axis so yes wedge is the correct patch type.
henry is offline   Reply With Quote

Old   August 31, 2005, 17:49
Default Thanks Henry. I tried a wedge
  #9
New Member
 
Amelia
Join Date: Mar 2009
Posts: 17
Rep Power: 8
amelia is on a distinguished road
Thanks Henry.
I tried a wedge with 5 and it seems to work fine for lower velocities (RE=2000). when I increase the angular velocity of the lid, the results present very high oscilations using both turbulent and laminar models. Do you have any suggestion?
amelia is offline   Reply With Quote

Old   September 4, 2005, 12:44
Default Hello, I am having problems
  #10
New Member
 
Amelia
Join Date: Mar 2009
Posts: 17
Rep Power: 8
amelia is on a distinguished road
Hello,

I am having problems reaching a stable convergence at higher Re, even using upwind schemes for all divSchemes except two. I noticed that it is not possible to select upwind scheme for div(R) term in simpleFoam. Is there a reason for this?

Also, is this scheme implemented in OpenFoam:

Khosla and Rubin scheme "A diagonaly dominated second-order accurate implicit scheme"?
amelia is offline   Reply With Quote

Old   September 4, 2005, 13:45
Default 1) What flux do you the upwind
  #11
Senior Member
 
Join Date: Mar 2009
Posts: 854
Rep Power: 13
henry is on a distinguished road
1) What flux do you the upwind should be evaluated on for the term div(R)?

2) No.
henry is offline   Reply With Quote

Old   September 4, 2005, 22:42
Default I am using upwind on the conve
  #12
New Member
 
Amelia
Join Date: Mar 2009
Posts: 17
Rep Power: 8
amelia is on a distinguished road
I am using upwind on the convection term and I am having many oscillations. Do you have any idea why?

In my simulations using a 3D mesh of the flume I had less oscillations, although the magnitude of the velocity was much lower than the experimental results.
When using the 2D mesh at lower Re, the numerical results were very good, much better than other commercial software I used before.
amelia 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
experimental or numerical data channel FELIPE Main CFD Forum 8 February 8, 2011 04:02
HELP! Experimental & numerical results don't agree Jenny Rollo FLUENT 5 April 23, 2006 14:12
NACA0012 experimental results. Kyung-Seok, Kim Main CFD Forum 0 March 13, 2006 06:46
Experimental & numerical results Amy CFX 2 September 1, 2005 08:52
searching for experimental results Vignesh Main CFD Forum 0 August 18, 2003 20:32


All times are GMT -4. The time now is 17:18.