What is the physical use of a streaklines in fluids? (not pathlines, streamlines or timelines)

[SirVonny]

TL;DR Summary

I have been looking around and trying to understand what the physical use is for a streaklines. While we are at it, maybe we can discuss how they differentiate from pathlines, streamlines and timelines as well as discussing their uses. Thanks for your feedback in advance.

Summary: I have been looking around and trying to understand what the physical use is for a streaklines. While we are at it, maybe we can discuss how they differentiate from pathlines, streamlines and timelines as well as discussing their uses. Thanks for your feedback in advance.

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[Baluncore]

Welcome to PF.
Start here; https://en.wikipedia.org/wiki/Streamlines,_streaklines,_and_pathlines

 

[boneh3ad]

I am not sure you could say there is a physical "use" for them, but it is important to know what they are and why they are not the same as streamlines. A common method of visualizing flow in a wind or water tunnel is to inject smoke or dye at a point and watch the trails they trace out over a body. If the flow is unsteady, this is a streakline and not a streamline. A tunnel user has to know this.