[Robotgroup] water flow

Leslie Filip lfilip at mac.com
Thu Aug 10 18:29:43 PDT 2006 

Mike,

Any idea what makes fabric softener fluoresce? It seems like this  
would be a lot less of an irritant since people wear clothes covered  
with it all the time. I have no idea how bright it is compared to  
other purpose-made chemicals, but it looked pretty good on that one  
episode of a little TV show called Lost where the CIA spook drew a  
map of the island on the back of a blast door. Probably no one has  
ever heard of this show before though ;  )

Les


On 10 Aug 2006, at 3:44 PM, Def Egge wrote:

> Of course, oil and water do not mix so well but, perhaps, that is  
> all right.
>
> Polyethylene oxide dissolved in low concentrations can drastically  
> alter
> the viscosity of water.  Glycerine, methyl cellulose, sugars, low  
> molecular
> weight alcohols, etc. are cheap, easily-obtained water-soluble  
> substances
> that might be worth experimenting with.
>
> Fluorescein, mentioned in an earlier post, though fairly non-tocix,  
> is a
> major irritant to skin, eyes, and mucus membranes.  It might be  
> wise to
> avoid triggering allergic / asthmatic reactions among onlookers.   
> [I seem
> to remember that the fluorescein-containing lasers created respiratory
> problems when they leaked in a lab I used to hang out in.]
>
> All the best....
>
>
> Mike
>
>
>
> At 14:58 2006/08/10 -0500, you wrote:
>> If we are talking about making water look pretty, perhaps you  
>> could add
>> some other fluid to the water to change its properties (viscosity or
>> whatever).  Oil comes to mind as a possibility.
>>
>>
>>
>> Leslie Filip wrote:
>>> Did you use angled blades that were in sync with the speed of flow?
>>> If this is not taken into account then the result sucks. FYI I am
>>> talking about blobs that are around a half inch in diameter, not
>>> sprinkle. I think a frozen arc of blobs is magnitudes more
>>> interesting than a single vertical stack of droplets, granted even
>>> those are pretty cool looking with the fluorescent dye and UV LEDs.
>>>
>>> I keep saying this so please if someone has seen otherwise correct
>>> me: "The start of laminar flow requires a ramp-up of speed within  
>>> the
>>> output chamber before exit." This is why trying to pulse blobs  
>>> with a
>>> plain valve does not work. It is the uniform speed and trajectory of
>>> water molecules in laminar flow as well as surface tension that
>>> allows the blobs to remain coherent.
>>>
>>> Looking forward to the party.
>>>
>>> Les
>>>
>>>
>>> On 10 Aug 2006, at 12:47 PM, brooksdesign wrote:
>>>
>>>
>>>> I tried several chopping type methods but none worked as good a my
>>>> sprayer hose valve thing in the sink .I have been messing with
>>>> chamber with water feeding in the side ,a nozzle on top and a
>>>> diaphram on bottom that can be pulsed by mechanical piston on a
>>>> crankshaft of with air pressure .I discovered this while rinsing
>>>> out a soap bottle ,good blobbieness .I'm building this as part of
>>>> the stage show I'm planning for the .....wait for it ....The last
>>>> party and official house dissassembly event at brooks' place in
>>>> Bastrop (no date yet but soon).
>>>> -brooks
>>>>
>>>> -----Original Message-----
>>>>
>>>>> From: Leslie Filip <lfilip at mac.com>
>>>>> Sent: Aug 10, 2006 7:29 AM
>>>>> To: Austin Robotgroup Mailing List <robotgroup at puremagic.com>
>>>>> Subject: Re: [Robotgroup] water flow
>>>>>
>>>>> If the blades are in a blower-type arrangement instead of a fan- 
>>>>> like
>>>>> arrangement it would chop the water more smoothly. The nozzle  
>>>>> would
>>>>> have to be shooting from within the cage though.
>>>>>
>>>>> Les
>>>>>
>>>>>
>>>>> On 10 Aug 2006, at 2:53 AM, Leslie Filip wrote:
>>>>>
>>>>>
>>>>>> Gray,
>>>>>>
>>>>>> I believe it is still laminar flow you are wanting, only that
>>>>>> instead
>>>>>> of constant streams you want blobs. In order to accomplish  
>>>>>> this the
>>>>>> material has to have a ramp up of speed inside the laminar  
>>>>>> flow tube
>>>>>> before it exits. In the examples I have seen, it was not  
>>>>>> possible to
>>>>>> have a series of closely spaced blobs using only control valves.
>>>>>> There may be a solution.
>>>>>>
>>>>>> If you have an arc of laminar flow water, I believe you could
>>>>>> mechanically chop it into blobs, removing the water where you  
>>>>>> want
>>>>>> space. Think of the way a jet engine's blades are tilted. As the
>>>>>> water passed through rotating blades the entry point and exit  
>>>>>> point
>>>>>> of the blades in the water column would coincide with the forward
>>>>>> motion of the water arc, thus chopping it into a series of small
>>>>>> cylinders. Then through surface tension, each cylinder would  
>>>>>> reshape
>>>>>> itself into blobs. It is the lack of uncontrolled angular  
>>>>>> momentum
>>>>>> that allows the blob to remain a blob.
>>>>>>
>>>>>> There is a limit to the speed at which the water can travel as a
>>>>>> blob, however. When the speed goes beyond a certain point, the  
>>>>>> air
>>>>>> pressure at the front of the blob destabilizes it. In a parabolic
>>>>>> arc, this is as true for the speed at which the water exits the
>>>>>> nozzle as it is for the descent.
>>>>>>
>>>>>> The arcs I saw in Las Vegas in some of the smaller water gardens
>>>>>> went
>>>>>> about 10-12 feet without a problem. The arcs are more prone to
>>>>>> destabilization than blobs due to surface tension and the  
>>>>>> differing
>>>>>> speed from one part of the column to another. I don't think there
>>>>>> would be any problem at all with blobs remaining blobs over this
>>>>>> distance.
>>>>>>
>>>>>> Les
>>>>>>
>>>>>>
>>>>>> On 09 Aug 2006, at 5:26 PM, Gray Mack wrote:
>>>>>>
>>>>>>
>>>>>>> What I am looking for is a term for creating liquid
>>>>>>> blobs. How big they can be and stuff based on driping
>>>>>>> from a drop tower or launched.
>>>>>>>
>>>>>>> Another approach- Put some LED's, a microcontroller, a
>>>>>>> capacitor, and an inductor+rectifier into a bunch of
>>>>>>> ping pong balls. Fire them from an air blower/cannon
>>>>>>> at synchronized intervals in an arch or straight down
>>>>>>> or through a clear pipe and when they land they roll
>>>>>>> to a hopper to be recycled. As they are loaded into
>>>>>>> the cannon the capacitor is charged through the
>>>>>>> inductor via a varying magnetic field at the cannon
>>>>>>> and instructions on when to light up are also sent
>>>>>>> through the field to each ball. The capacitor has
>>>>>>> enough power to blink LEDs a few times during its
>>>>>>> travel as directed by the cannon.
>>>>>>> -Gray
>>>>>>>
>>>>>>> --- Shane Geiger <sgeiger at ncee.net> wrote:
>>>>>>>
>>>>>>>
>>>>>>>> FYI:  http://en.wikipedia.org/wiki/Laminar_flow
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> Paul Atkinson wrote:
>>>>>>>>
>>>>>>>>> Gray,
>>>>>>>>>
>>>>>>>>>   I don't think you'll have a problem if you
>>>>>>>>>
>>>>>>>> aren't susceptible to jitter between pulses (as
>>>>>>>> stepper motors are.)
>>>>>>>>
>>>>>>>>>   You may have to have a special driver (giveio)
>>>>>>>>>
>>>>>>>> or something like that to access the parallel port
>>>>>>>> under Win XP/NT/2k if memory serves.
>>>>>>>>
>>>>>>>>>   The opposite of laminar flow is turbulent flow.
>>>>>>>>>
>>>>>>>>>   Paul
>>>>>>>>>
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>>
>> -- 
>> Shane Geiger
>> IT Director
>> National Council on Economic Education
>> sgeiger at ncee.net  |  402-438-8958  |  http://www.ncee.net
>>
>> Leading the Campaign for Economic and Financial Literacy
>>
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