CFD Online Logo CFD Online URL
Home > Forums > General Forums > Main CFD Forum

plot streamlines

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

LinkBack Thread Tools Search this Thread Display Modes
Old   December 18, 1999, 09:09
Default plot streamlines
Posts: n/a
I have got the velocities data from CFD program developing by ourself and want to plot the streamlines. Could anybody tell me how to plot the streamlines ?
  Reply With Quote

Old   December 18, 1999, 12:00
Default Re: plot streamlines
John C. Chien
Posts: n/a
(1). To draw a fluid particle path (or trajectory)(x(s),y(s),z(s)) from the velocity field (u,v,w), you first start from a known velocity location (x1,y1,z1,u1,v1,w1) and calculate the second point location(x2,y2,z2), based on the velocity vector(u1,v1,w1) and the specified distance (ds). (like driving a car with steering wheel fixed at the initial position.) (2). At the second point(x2,y2,z2), you can repeat the process. It is likely that the velocity at the second point(U2,v2,w2) is not available. In this case, you will have to use interpolation to calculate the unknown velocity vector. (3). That's all. It is very simple and straight forward. (naturally, in order to get accurate particle path, you will need fine mesh solution for the velocity field as well as small integration step size. Other wise the car will hit the curve on the side of the road.)
  Reply With Quote

Old   December 20, 1999, 12:21
Default Re: plot streamlines
Posts: n/a
(1) John's suggestion plots particle trajectories, not streamlines

(2) but the result is almost the same, if you use the current velocity (constant in time)

(3) because streamlines are everywhere parallel to the (current) velocity => John's suggestion is ok

(4) streamlines are contours of the streamfunction: if you have a good program for contour lines, try the following:

(5) compute the streamfunction psi by solving: rot rot psi = rot v (rot ist the rotation; see a book about vector analysis)

(6) for FE-programs the above equation looks like (rot psi, rot phi) = (v, rot phi) for all phi

(7) boundary conditions for psi: (7a) psi = constant on walls and other boundaries with v normal to wall = 0 (7b) d(psi) = v*normal on other boundaries

(8) compute and plot contour lines of psi

(9) for plane geometry, rot rot degenerates to the laplace-operator; for rotational symmetric geometry, look into an text book for vector analysis (calculus)

  Reply With Quote


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
CFD-Post how to plot stress and streamlines? Airone CFX 3 July 9, 2010 11:56
Plot streamlines DAKA Main CFD Forum 1 May 10, 2010 08:49
How to plot streamlines with VisIt qtian OpenFOAM Post-Processing 1 February 28, 2008 15:35
How to plot streamlines...? sushii FLUENT 2 October 26, 2007 06:06
Streamlines plot Yticitrov Main CFD Forum 2 August 24, 2004 20:36

All times are GMT -4. The time now is 23:36.