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Latest comment: 18 years ago1 comment1 person in discussion
I think that in explaing one term it makes sense to explain the others, prehaps rename the article Streamlines, Streaklines and Pathlines? Already this article deals with all three so it would be much work. Rex the first08:23, 20 April 2006 (UTC)Reply
Latest comment: 17 years ago4 comments2 people in discussion
The article states that streaklines are found by injecting smoke into a wind tunnel from one point. How is this different from streamlines? —Ben FrantzDale02:22, 29 April 2007 (UTC)Reply
Hmm, I am not an engineer so I do not know how streamlines are measured I can only say that injecting smoke from a point would measure the streaklines and not the streamlines (unless the flow was steady). If the flow changed direction (for example it was pointing up and it now points left) then the smoke would show the path that the flow did take in the past (streaklines), not the path parallel to the flow at a given instant (streamlines). Rex the firsttalk | contribs21:04, 29 April 2007 (UTC)Reply
OK, so for steady flow, streamlines are the same as streak lines?
Latest comment: 13 years ago3 comments2 people in discussion
I think there may be a minor error in the article (I believe that radius is a scalar and thus has no direction) :
"The radius of curvature of the streamline is in the direction of decreasing radial pressure."
Could someone knowledgeable in the subject correct it? Thanks much.
Mark.camp (talk) 01:31, 12 February 2011 (UTC)Reply
I have changed the sentence to "The center of curvature of the streamline lies in the direction of decreasing radial pressure." Dolphin(t)05:34, 12 February 2011 (UTC)Reply
Thanks, Dolphin. That looks good. Truth be told, on re-reading my post, I remembered that radius IS often treated as a vector! But I still like your text, which treats it as a scalar, better.
Latest comment: 10 years ago1 comment1 person in discussion
Why not give the streamlines as initial-value ODEs like the streaklines and pathlines? Also, it might be stressed that pathlines are spatiotemporal lines while streamlines
are only spatial lines. — Preceding unsigned comment added by 62.16.179.14 (talk) 20:48, 7 August 2013 (UTC)Reply
Article covers many important aspects, but still needs more figures showing different streamline/streakline patterns in flows.
Possibility of adding timeline which are also used to describe/visualize a flow. Timeline describes the deformation of adjacent fluid particles as they move around.
Also can add vortex line, which is same as streamline but instead of velocity, it is tangential to vorticity ().
In case, these lines are added, would be a better idea to change the title of the page to say something like, flowfield lines.
Latest comment: 7 years ago1 comment1 person in discussion
It might be easier to understand the concept if several pathlines were connected to the origin in the gif. This could demonstrate the generation of the streakline a little more clearly.
I cannot seem to run that code in maxima and don't have access to mathematica.
Latest comment: 2 years ago1 comment1 person in discussion
Contrary to what is written in the article, streaklines can self-intersect, and also intersect other streaklines. A simple example for this is the following flow field:
which is a (counter-clockwise) rigid body rotation with a superposed constant horizontal translation. A streakline starting at will intersect itself twice. See also animation below which shows the pathlines of the emitted particles (emitted every 0.5 time units) and the streaklines. Both are analytical solutions.
Indeed, it is no problem for a marked particle to fly by its emission point again. If the flow field at the initial position has now changed, the streakline intersects itself from this point on.
There is also literature available that disputes this statement on theoretical grounds, e.g. Qinghai Zhang and Lingyun Ding (2019) Lagrangian Flux Calculation Through a Fixed Planar Curve for Scalar Conservation Laws, SIAM Journal on scientific computing (Volume 41, Issue 6).