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Water Tunnel Build Tips/Help/Review? (help greatly appreciated, extensive project)

  1. Oct 14, 2011 #1
    Hey, so i'll just start this by saying that any/all info i present here may be wrong, i've only got physics 20 under my belt right now but i've been doing a ton of research, so if i seem like i don't know what i'm talking about, it's because i probably don't. I'm in grade 12, and i'm interested in fluid dynamics, so i figured i'll build a water tunnel in my spare time. I figured it couldn't hurt, i could probably use it as a project for Phy. 30 and then i can use it later on in university, maybe do some tests with it, hey? But if i'm gonna do this, I wanna do this right. Take ALL Variables into account, and i mean everything. This is definitely something i want to be able to use, and possibly to let other people use as at least a semi-legitimate experiment source. I was thinking of possibly using a fish tank as the main flow chamber, haven't figured out what size yet though. i was thinking of using either small sections of PVC pipe glued/caulked to the inside of the tank or something along those lines as a honeycomb baffler, and i'm willing to spent the time filing them to round the trailing edges if you think that would give a more laminar flow, although i know for sure that i'm going to be using slow flow speeds (i don't know what these would be though. if anyone has any recommendations for a good slow baseline...?). I was toying around with a 2 pump/2 tank system, one pump for water and one for (possibly?) oil, which i was thinking of using as a visualization medium if it wouldn't create turbulence b/c of the different densities? after the flow observation tank i was thinking of having either a large section of PVC pipe or a thick section of hose (possibly 2 hoses, depending on the rate of flow through them and what would cause the least turbulence) connecting the main tank to a second holding tank where the oil would (hopefully) collect on the top of the tank where a second/third smaller hose with a pump attached would move the oil to a series of hoses or possibly something smaller (plastic syringe needles?) sealed into the inside of the tank which would distribute the oil into the laminar flow inside the main tank to act as a visualization medium, as mentioned above. A third/fourth hose sealed to the bottom of the holding tank would pump water into a large section of PVC pipe connected to the front of the main tank, starting the system over. This might seem unfeasible, if so please tell me because i don't want to get halfway through building this only to figure out that it won't work/won't work as well as i want something i built to work, but i THINK that if i can match the flow rate of the oil pump with the flow rate of water/oil mixture coming into the holding tank, i can keep a fairly constant fluid level in both tanks. My main problems/questions are: Will any oils work as valid visualization mediums, and if not then what will, other than dyes or styrofoam pellets? ( I don't want to mess around with the filters in the pumps TOO much). If oils will work, will there be any KH instabilities cause by the differing densities of oil/water? and are there any obvious flaws with this design or anything that you think i could improve in it? If you managed to read this far, thank you SO MUCH for your time, i know you'll be a huge help to me in this build. Either leave a comment or message me if you're interested in helping me out. Thanks again.
     
  2. jcsd
  3. Oct 14, 2011 #2

    boneh3ad

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    Re: Water Tunnel Build Tips/Help/Review? (help greatly appreciated, extensive project

    Oil won't work because of its lower density. It isn't an instability that you will have to worry about, but simply the fact that the oil won't follow the flow but will tend to rise. Your visualization will be wrong. That is why most water tunnels use dyes which are neutrally buoyant. You are better off just using dye and changing out the water when it gets too colored.

    I think a picture would be helpful as well, especially so we see what kind of relative scales you have for your pipes vs. your aquarium. Depending on all that you may have a rough time getting a flow rate that is useful.
     
  4. Oct 14, 2011 #3
    Re: Water Tunnel Build Tips/Help/Review? (help greatly appreciated, extensive project

    Ok. I was hoping to avoid using dyes because i didn't want to have to change the water, but since there isn't really any way around that i guess i'll just have to live with it. i might look into seeing if i can get some filters to put in the holding tank so i don't have to change it as often also, but that's tentative. As for photos, this is all still in the planning stage, i'll probably start building it in 2 months or so, but when i do i'll put pictures up for anyone that might be interested in seeing how it's going. I would try to draw a picture of it to aid in explanation, but it would probably just make you confused. The final number/placement of hoses or PVC pipe connecting the main tank to the holding tank will be completely dependent on the flow rate and what would work best though, over the build i'll be doing calculations to figure out what would cause the least turbulence and allow for the highest useful rate of flow through the entire setup. Thanks for replying though man :D you just saved me the expense of building it and then having to completely change the setup. Have a good one.
     
    Last edited: Oct 14, 2011
  5. Oct 16, 2011 #4
    Re: Water Tunnel Build Tips/Help/Review? (help greatly appreciated, extensive project

    Also, if anyone reading this has any more comments or tips on what i could do to improve this, feel free to voice them. i'm really hoping i can make this a viable, well-built tunnel. Thanks for the help :D
     
  6. Oct 16, 2011 #5

    boneh3ad

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    Re: Water Tunnel Build Tips/Help/Review? (help greatly appreciated, extensive project

    Draw up some sketches. Your desired flow rate should dictate your design, not the other way around.
     
  7. Oct 18, 2011 #6
    Re: Water Tunnel Build Tips/Help/Review? (help greatly appreciated, extensive project

    Ok. It'll probably take me a while, when i'm done them i'll post them. It shold be about a week or two, i need to work around school and extra-curriculars also.
     
  8. Oct 18, 2011 #7

    boneh3ad

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    Re: Water Tunnel Build Tips/Help/Review? (help greatly appreciated, extensive project

    It doesn't have to be like engineering drawings. Just make a quick sketch of what you had in mind and that would at least be a starting point.
     
  9. Oct 29, 2011 #8
    Re: Water Tunnel Build Tips/Help/Review? (help greatly appreciated, extensive project

    Sorry that it's taking so long, i'm doing scale drawings because a few of my teachers at school wanted to see what it would look like and then i can use those drawings in a project that i do with it later. So when i eventually do get the drawings up, there will also be a few pages of calculations that go with it.
     
  10. Dec 8, 2011 #9
    Re: Water Tunnel Build Tips/Help/Review? (help greatly appreciated, extensive project

    Hey,
    Sorry it took so long for me to get back online with this. School has kinda been making me forget about life, Long story short this has been about a half a month's work. I've been searching online, and i've already got the large aquarium sitting in my basement. I've been looking at some diamond cutters to drill holes in it for the pvc pipes, but i'm not gonna start on this until next semester (January) so that i can get my physics teacher to help me with some of it. There's 3 more files also, if anyone has any confusions about the pictures feel free to ask, i know my writing is pretty messy so you might not be abkle to read the smaller print. Thanks once again for helping me out with this.
     

    Attached Files:

  11. Dec 8, 2011 #10
    Re: Water Tunnel Build Tips/Help/Review? (help greatly appreciated, extensive project

    Also, I know earlier i said scale drawings.. I've been busy with school. Scale drawings will be coming when I actually build the thing in semester 2.
     

    Attached Files:

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