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asheronscall1234 (December 31, 1969 at 6:59 pm)
Err no. Smaller witdth means higher flowrate and hence lower pressure, from bernoulli. Easy to see in a Venturi tube. But you don't need that for the theory of 0:47Open rivers are not really relevant to your case. All that you have to use is conservation of mass. All the water that comes in in the wide part, has to come out on the smaller part. That means that it has to come out a lot faster on the small end. (regarding water as incompressible).To conclude: really cool video!
DJPish (December 31, 1969 at 6:59 pm)
If you have a 1m wide river with a flow of 3.4 m/s and you cut it of to a width of only 1cm, you get a river with the same flow as the spd of sound. I bet you can see the wierdness in that.However, if you do it, as with the flow nozzle, in a closed system, the theory works. This is easy to verify with Bernoullis principle. If the width of the pipe is made smaller the pressure increases and, to compensate that, the dynamic pressure must increase, which means increased flow. I suppose..
gryphern (December 31, 1969 at 6:59 pm)
I'd appreciate feedback on that--we based it off of two of our old college physics textbooks, but textbooks aren't always accurate.
DJPish (December 31, 1969 at 6:59 pm)
The theory during 0:47 is very wrong. This is only true in a closed system.
yeffrey1 (December 31, 1969 at 6:59 pm)
Cool! Thanks for the reply.Built my laminar nozzle last night, just need to glue it together as it's in beta stage right now. I'm going to pick up a surplus motor and make a disk to create water jets. I'm planning to use old whiskey barrels, the kind they use for planters, with dark mesh over the top and a plexiglass splash guard. Hopefully I can find a decent, inexpensive pump so I can have jumping water in my garden! Thanks for the great video and the helpful response!
gryphern (December 31, 1969 at 6:59 pm)
You need a pump that can put out a constant flow with the gallons per minute you need, "GPM." Compare the fountain you're making with commercial set ups, they have installation manuals on the web and you can glean useful knowledge from them. On the date of this post inyopools * com has the specs and installation for Jandy brand laminar heads posted, included suggested minimum flow rates.
gryphern (December 31, 1969 at 6:59 pm)
There are different ways to cut off the flow. We tried the disk idea and it works, but you have to have a splash guard of some kind, or install the whole unit in a box/buried to hide maximize the effect. You'll need a power source of some kind to power the disc, powering the disc spinning using the water pressure from your source doesn't work, since the jet, when cut off and splashing onto the disc, adds friction and stops the disk.
gryphern (December 31, 1969 at 6:59 pm)
To make light appear to jump along the laminar jet mount a $1.49 pet toy laser pointing into the flow at either end, the laser needs to hit the inside of the flow at a 48 degree angle. Because the water is laminar you can only see the light from a few angles unless you add something to scatter the light.Brush something fuzzy, like the top of some grass that has gone to seed along the edge of the flow near the outlet. Where the grass introduces bubble and turbulence the flow lights up.
yeffrey1 (December 31, 1969 at 6:59 pm)
This is deeply nifty!I had a couple of questions:1) How do you mount the lasers to do that nifty coloured light thing?2) How do you make it shoot little curving bullets of water instead of a constant stream? Could you perhaps keep the flow moving but have a rotating disc with holes so it blocks the flow sometimes and lets jumping water through?3) Do you think it's possible to produce the pressure necessary with a consumer-grade fountain pump resulting in a closed system?Thanks for posting!
gryphern (December 31, 1969 at 6:59 pm)
There's a lot of folks, particularly young folks, whom the record and movie industry have scared crapless about intellectual property rights, and well-meaning but uninformed authority figures have taught that they can't touch to the point where they don't know if they can quote a song in a poem. What made you immediately respond that it was copyrighted? Did you think the video was somehow illegal? This could be a good excuse to learn about intellectual property laws in the US and abroad. |
