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Particle path won't go all the way!

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Old   January 23, 2014, 23:00
Default Particle path won't go all the way!
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YunJi Choi
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Hello,

I have an unsteady, internal and two phase flow CFD simulation data to post process with Tecplot 360 2011.

I am having an issue with streamtraces function. When I create stream traces, it gives me short tangled lines that stretches and shrinks over time. What I would really like instead is a path a single particle followed over the entirety of my simulation.

There is only one path for a particle to follow over the simulation, hence the line should not be changing its shape over time. I would really appreciate your help. Please let me know if anything is not clear in my question. I will clarify them.

Please see the image I have attached.

As you can see, there are three streamtraces I have created. They do stretch and shrink over time when I play the animation. Why would they? I thought streamtraces supposed show a single path the particle has followed overtime? Shouldn't there be only one line for a particle where each point of the line represents the location the particle at a certain time (together they would form a line)?

Another confusion, may be the biggest one, is what is the difference between streamtraces and Particle paths and streaklines under analyze? When I read tutorials and users meanual, streamstraces appears to be what I want, however, at this point I would like to understand the relationship between streamtraces and particle paths. Is there any good resource to dig in other than user's manual?

Thank you!
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Old   January 24, 2014, 12:35
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Scott Rumage
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This link from Tecplot’s knowledge base may be helpful about your question on streamtraces and particle paths:

Problem: How can I create particle paths in steady state flow? With unsteady flow?
Solution: In Tecplot creating streamtraces will show you massless particles with steady state flow. With CFDA the default condition for creating particle paths is steady-state. If you want to specify unsteady flow then you need to identify the time levels in the Unsteady Flow Options dialog. Also CFDA allows you to perform a particle path calculation with steady-state or unsteady-state with particles with mass. It also allows the creation of Streaklines which are the lines created by periodic (frequent) releases of mass-less particles at the same location. For steady flow Tecplots streamtraces massless particle paths and streaklines are all the same.

There is also a nice white paper on the difference between streaklines, particle paths, and streamlines on Tecplot’s web-site titled: Streamlines, Particle Paths, and Streaklines. To access it, create a Tecplot web account here: http://www.tecplot.com/login/?redirect_to=/dashboard , and then go to the “White Papers” section under the “Learning” menu. Once in that area the article you want is the sixth item on the list.

While at the Tecplot web-site you might explore the Tecplot blog to get other user tips on using the application.
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