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i've been looking around for an answer but it turns out that google dsn't think it's an obvious question. Would really appreciate the help.

Basically i'm wondering if there is any known material that suspends in water regardless of any force that is present in an enclosed container completely filled with water.

The material can be a colored liquid to be able to see changes when external forces are applied. Take for instance a wind tunnel when studying aerodynamics but rather than having the wind/smoke be the variable and the object the constant. I want the smoke to be the constant and study how it [the smoke] behaves when something goes through it. But in water.

So lets say i want to study the hydrodynamics of a miniature submarine passing through a water in a container Considering that the water is completely and utterly still. What material can i use?

I hope i was clear enough with my question, please let me know if there is something i could clarify. Thanks!

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  • $\begingroup$ What kind of timescales are needed? For instance, if you are only running an experiment over a matter of seconds, is it okay if your tracer would eventually settle down but it took X minutes to do it? Or will your body by moving for long periods? Will you need to wait until the tank is 100% still (taking hours or days to settle)? $\endgroup$
    – tpg2114
    Jul 9, 2015 at 21:21
  • $\begingroup$ Also, is it submerged or will it run on the surface of the water? $\endgroup$
    – tpg2114
    Jul 9, 2015 at 21:23
  • $\begingroup$ Hey tpg thanks for the reply. Actually water doesn't need to be completely still throughout the experiment. What's more important is the "tracer" which needs to distribute itself in an almost homogeneous manner. Edit: But when the object goes through it, the tracer needs to acts independently from the water so that the forces that are created by the object are visible. $\endgroup$
    – Ti8
    Jul 9, 2015 at 21:26
  • $\begingroup$ You might have a hard time with that -- the reason moving through a smoke-filled chamber will create disturbances is because there's entrainment of non-smoke filled air into the chamber. Imagine driving your car through a dense fog -- there isn't any noticeable features behind you because the medium is homogenized. You'll have the same issue in a finite tank of water with a dye or tracer. What are you trying to accomplish by moving the body rather than the fluid? $\endgroup$
    – tpg2114
    Jul 9, 2015 at 21:32
  • $\begingroup$ What i'm trying to accomplish is to visibly be able to see the shape (or movement) of the current produced by the movement of the object through the water. For tracer, is there something more granular that i can use? Rather than a colored liquid? For example, if you watch a video of a lake, underwater, u tend to see particles floating about as if suspended. Maybe it could be something similar? Perhaps i need to change the the liquid entirely? $\endgroup$
    – Ti8
    Jul 9, 2015 at 21:42

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There are lots of tried and tested methods for visualising flows, for example mica or aluminium flakes though these tend to settle fairly quickly. In days gone by I used zirconium phosphate that had been delaminated by titrating with tetramethyl ammonia. This gives very thin flakes that are stable to sedimentation for a day or so, though you have to prepare these yourself and my notes on how to do so are now locked away in the vaults of Unilever Research. Others in my group used lamellar liquid crystals, though as I recall the requirements of generating the lamellar phase limit the concentrations you can use.

I would have a Google for flow visualisation flake and flow visualisation liquid crystal for lots of related articles.

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