CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > CD-adapco

Streamline plot

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

Reply
 
LinkBack Thread Tools Display Modes
Old   January 8, 2005, 04:59
Default Streamline plot
  #1
C.Bhasker
Guest
 
Posts: n/a
Can some one help to create stream line plot for the three dimensional problems solved in Star-CD. In Star-CD Post, no direct option is available to create streamline plot. Looking forward to receive the hints.
  Reply With Quote

Old   January 8, 2005, 07:43
Default Re: Streamline plot
  #2
Jörn Beilke
Guest
 
Posts: n/a
You have to look for "partickle tracks". Streamlines only exist in 2d.
  Reply With Quote

Old   January 9, 2005, 03:28
Default Re: Streamline plot
  #3
Anton Lyaskin
Guest
 
Posts: n/a
... and you can plot them as countours of stream function (becomes available when you choose Cell and Wall/Bound data)
  Reply With Quote

Old   January 9, 2005, 23:50
Default Re: Streamline plot
  #4
C.Bhasker
Guest
 
Posts: n/a
Mr Anton Lyaskin:

Your hint has successfully worked in creation of streamline plot for 3d problems. Thanks lot! I am finding some problem in creating the blocks using best fitted shapes of circular geometries. (precisely, block line forms straight instead of of following arc).t will be highly beneficial if you provide me an hint.

Alternatively I have successfully established the close link for the grids generated in Altair's Hypermesh to Star-CD and then to Tecplot.

Can you please clarify for import of gambit grids along with regions in star-CD which I am unable to do so ofcourse, if you worked.

Regards,

  Reply With Quote

Old   January 10, 2005, 04:05
Default Re: Streamline plot
  #5
Anton Lyaskin
Guest
 
Posts: n/a
Concerning the blocks, there are 2 possible reasons. 1. The corners of your block are not belong to a spline forming the arc (go to spline tool and check the numbers of the end vertices of the spline, then check which vertices are specified for the block). 2. It's a bug in displaying the blocks with spline edges (I've encountered it a couple of times, just try to generate mesh for the block).

For importing Gambit grids I have no experience, sorry.
  Reply With Quote

Old   January 10, 2005, 06:05
Default Re: Streamline plot
  #6
C.Bhasker
Guest
 
Posts: n/a
thanks!
  Reply With Quote

Old   January 12, 2005, 02:21
Default Re: Streamline plot
  #7
C.Bhasker
Guest
 
Posts: n/a
Mr Anton:

In some cases, under cell and wall data, stream is not getting and following message is displaced:

POST*>

getv,all,stream **NOTE - REALLOCATING MEMORY **NOTE - DENS IS CONSTANT (NOT SOLVED FOR) VECTOR COMPONENT U STORED VECTOR COMPONENT V STORED VECTOR COMPONENT W STORED SCALAR ITEM DENS STORED ***ERROR - THE MODEL IS NOT TWO DIMENSIONAL ** STREAM FUNCTION CANNOT BE CALCULATED DUE TO ABOVE ERRORS

in some cases above error is not displayed. I have compared this problem output with the other problem output and not found any difference in steup.

Kinldy know the possible hint to correct the above error.

bskr

POST*>
  Reply With Quote

Old   January 12, 2005, 05:15
Default Re: Streamline plot
  #8
Anton Lyaskin
Guest
 
Posts: n/a
Stream function can be plotted for 2D models only (i.e. those which has one layer of cells with symmetry boundaries). And sometimes it can't be plotted even for them It's some kind of a bug, I've couldn't figure out the reason
  Reply With Quote

Old   January 12, 2005, 05:22
Default Re: Streamline plot
  #9
Brian
Guest
 
Posts: n/a
The two-dimensional form of the Navier-Stokes equations can be re-written in the so-called stream function / vorticity formulation. This can NOT be done in three dimensions, so both vorticity and stream function are constructs that exist in two dimensions only. As a streamline is a contour of constant stream function, there is therefore no such thing as a streamline in three dimensions.

There is an expression for the definition of stream function in terms of velocity and other variables. It is this expression that is applied when you plot stream function (GETV STRE) in Prostar.

However, while calculating the expression, the code checks to see whether your mesh is truly two-dimensional. If it discovers that it is not, the error report you mention is issued.

So you need to look closely at your mesh - do you truly have only one cell thickness everywhere in the third dimension?

You can always "fake" three-dimensional streamlines by creating droplet or particle tracks, with zero particle mass (zero size). These particles will exactly follow the flow, and thus resemble streamlines, even though they are not really.
  Reply With Quote

Old   January 12, 2005, 15:14
Default Re: Streamline plot
  #10
MG
Guest
 
Posts: n/a
To import gambit mesh, first save the mesh as .NEU file in gambit. In starcd, type: gamb, FILENAME

  Reply With Quote

Old   January 12, 2005, 23:30
Default Re: Streamline plot
  #11
C.Bhasker
Guest
 
Posts: n/a
Thanks for your hint. I have already done this and successful in reading gambit grids in star CD and happy about it.

-bskr
  Reply With Quote

Old   January 12, 2005, 23:38
Default Re: Streamline plot
  #12
C.Bhasker
Guest
 
Posts: n/a
To test this, firstly I have created 2d sketch in xy plane and later extruded to z dimension (uniformly) I have created the grid using best shaped blocks. I have set up this and solved in post when loaded cell/wall bound data stream is successufully loaded.

In similar way I have tested another geometry of slightly different shape and solved. This time in post under data, under cell/wall bound data, stream is not getting loaded. I think support guys of Star-CD should look at this and respond for correction.

Your suggestion for plotting streamline with zero particle mass is excellent. I will try and come back.

Thanks for your response.

bskr
  Reply With Quote

Old   January 12, 2005, 23:44
Default Re: Streamline plot
  #13
C.Bhasker
Guest
 
Posts: n/a
Mr Anton:

Thanks for your response.

I hope support guys at Star-CD may looking at these messages and some correction to this bug follows in coming days.

I have successfully read the gambit grids in star-CD files as neu extension in star-CD and happy about it.

-Bskr
  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
plot streamline taw Main CFD Forum 6 August 16, 2009 12:26
How to plot streamline for 2D case? Feng FLUENT 2 November 13, 2006 16:28
Streamline plot. Sham FLUENT 1 September 16, 2005 04:13
streamline plot P.kalyanakumar CD-adapco 2 July 30, 2005 02:16
CFX 5.5.1 Streamline Plot Satchit Panse CFX 3 March 8, 2005 12:58


All times are GMT -4. The time now is 09:05.