Large volume laminar flow machine

[karimwassef]

Here are the new numbers:
To move 24" x 24" at 1in/s for 5 seconds one way:

The volume moved is 12gal at 9000gph, weighing 104lbs

Using 1/8th inch diameter straws, the flow is laminar with a length of 0.7in (smaller box). So the laminarizing box only needs to be 3.5" thick including plumbing.

The Torpedo pump should work if its reef safe. At 1000W, it's 1% efficient.

I'll look at the actuated pistons' math next.

[karimwassef]

Taking all the piston ideas, here's what I'm thinking.

The pistons pushing up and down take up the least room from a practical implementation. The problem is that they create an up/down wave.

But using them as a bellows instead means that the depth of the tank can be converted into a sideways push. So, the motion is downward in a sealed box. That moves water that is channeled to point to the right. That's passed through the laminarizing box.

Two boxes on either end, one pulling water in, the other pushing water out. Synchronized.

[karimwassef]

How's this?

[karimwassef]

greater detail



if the piston is thin, then the injection box is 24" x 24" x 5".

I'm not confident in a seal without a large piston, 6" deep, or even 12". If the piston is 12", then the injection stage needs to double to 10": 24" x 24" x 10"

The baffles may be another 3"?

The laminar section is ~ 3"?

So 24" x 24" x 16" .... still big, but closer I think.

[herring_fish]

“Roll the historical film - imagine shimmering memory clip here –“

Yes I have followed your work for a long time. I remember most of those pics. I have planned to copy some of your work but can’t try your new endeavor. Baby steps first.
Unfortunately, I am dyslexic so I mostly look at the pictures and didn’t read all of the text. Remember, I’m a guy ….”I don’t need to look at the directions.” …or do I?


I don’t remember getting all of the feedback on how your stuff worked.

“The difference is that the change in direction is sinusoidal. The laminar flow's timing isn't.”

It depends on where you are and when. Where you were, the reef itself didn’t thin out the body of water. It was moving much like it was all in a box on casters, shifting back and forth. (ignore the surface wave in the box)
At other paces, the reef causes the water to up-well and push over the reef structure causing a longer, more sinusoidal flow …even though it can be laminar. What you are trying to do is ambitious and requires a lot of power as you have already calculated.

I am looking at something like the 12 by 12 idea that you talked about. …understanding the down sides.



Going back to the full blown idea…

When I am brain storming, as you know, I think outside the box. (way outside!) As I was taught, bad ideas can be improved or fixed ….or can spur better ideas. So when it comes to ideas, I believe in quantity not quality. That is why I will just utter whatever comes to my mine, no matter how stupid it sounds.

I guess everyone that is reading this thread has mentally explored an external, open topped box above the tank with a baffle going back and forth. This external box has been done before. Often pushing and then pulling something with the same force saves energy over two separate units pushing at a different work output as when it is pulling or just reacting to the work of the other unit.

If the baffle and the sides of a rectangular vessel was taller than the resting waterline, the waves would not wash over. You would not need seals, just a close fit, not touching the walls. Seals would assuredly wear out in no time. At least that is what I have read. On the other hand, water blow by wouldn’t be that great as long as the waves didn’t over flow the baffle or sides. The water that goes upward in a wave would, of course come back down and act as a capacitor so energy would not be lost.

The vessel would not have to be made of glass so you wouldn’t have to worry about accumulated stress fractures and sudden catastrophic failure of the display tank. A problem would go back to piping the water to the two ends of the tank with minimal friction, also addressed earlier.

The narrow boxes at either end is the only thing that I have been able to think of over the years. Not being a fluids guy, I wonder if you would need the internal baffles. If the pressure inside the box exceeds the resistants’ of the straw wall, won’t the out flow be pretty close to equal without the baffles?
Now the main moving drive baffle (say, going left and right) would extend down into the vestal at a right angle. There would be a long moment or torque length produced by the long baffle so there would be a lot of stress on the slide mechanism that the drive baffle would be attached to. A geared motor could move the baffle left and right like a piston, piston rod and crank shaft in a car, only in reverse.

Again, I am probably not explaining anything that we have not all thought of before but it might cause someone to come up with a better idea.

[karimwassef]

Thanks herring. Can you draw out your baffle box? I need to visualize it better.

I agree that the injection box doesn't need to be a super tight fit. I also agree that the baffles may not be needed due to the back pressure of the laminarizing box.

I am concerned with the pressure in the injection box. It might be so large that acrylic may not be a viable material.

The left/right pistons with a motor/gear/bar... I hear what you're saying about not needing a seal, just high walls. This supports erica's approach too. I'd need to mock it up, but you both may be right. I'll look at it again.

[karimwassef]

On a more fundamental level, I was reading back on this thread and I've got a couple of glaring errors in logic and calculations.

I've been looking at the box of water being moved as a 24x24x20". This is wrong. If it were true, then that little subset of tank volume would represent a wave that moves through the tank. It doesn't represent the bulk of the tank moving to the right or left.

From a calculation point of view, I'm actually trying to move the 6' of water between the ends to move at 1in/s. So the power needed is much larger.

For a logical point of view, pushing against the bulk of the tank water at one end and pulling at the other end will not make the middle bulk of tank move left to right! It will create two opposing waves that will move depending on the properties of the medium (water). Each wave will propagate from its initiation point to the other. Left to Right + Right to Left.

If they happen to add up perfectly, I could have a standing wave. That I don't want. If they don't, I'll just have two laminar waves pushing through the tank in opposite directions. If they cancel perfectly, I think this could look like the bulk of the tanks is moving, but it will only happen after several cycles.

So, there is another level of design missing here. The timing and speed of the action (pump or piston) needs to be engineered.

I don't think there is a mechanism to move the middle bulk of water by pushing on the sides... the density and viscosity of water won't allow it unless the tank is very short. That's my conclusion so far.

[karimwassef]

For those on this journey with me, here is my new favorite website.

http://www.insula.com.au/physics/1279/L14.html

It explains the longitudinal waves I was describing above as if it was written as a response to what I wrote! It's excellent.

[herring_fish]

I haven't looked at the web sight yet but here goes anyway. Most of that is about waves. You don't want wave action.

I read a lot of my stuff on wave action and water movement in Dr. Adey's Dynamic Aquaria

I will get on the graphic.

As for the volume of water that needs to be moved, yes you have to move it all at the same time, including what is not seen. That is a lot of force! Industrial!

If you have a longer cycle time, you don’t have to worry (as much) about the wave action. Moving water that fast would cause things that are slightly akin to cavitation. Again, you would need to also have extra room above the display tank for wave overflow.

[karimwassef]

Here is a pressure (longitudonal) wave created by a forcing wall on the left. In this case, it's bouncing off the right wall and interacting with the original wave.



It's different than surface (transverse) wave that we're used to



Here's what happens with both



All credit to the website I listed and Dr. Russell reference in it.

[karimwassef]

Here is the animal from Dr Russell's website

http://www.acs.psu.edu/drussell/Demo...dingWaves.html

showing a standing longitudonal wave



I think this is as close as I can get to creating a bulk motion flow in a closed reef tank? It basically sets up multiple zones of high flow or no flow depending on the length of the tank and the wavelength.

So instead of one bulk motion, it forms multiple motion blocks. That might actually be better. It would allow placement of corals that prefer high flow and others that prefer low flow in the same display.

[herring_fish]

This is not to scale and the rotation is not at the right point but I hope that this helps.

The (Blue) baffle moves left and right. It is attached to a carriage on a slide rail. There is a BIG rotating wheel that has to be the size of the displacement. There are ways to get around that but you get the idea I hope. As the wheel turns, it moves the carriage.

The baffle would create wave action that might be violent. The fact that the baffle is so long means that as you push it in the water, it will want to bend ...and the wheels on the track will want to bind because of the up and down pressure as the baffle wants to rotate instead of just push in a straight line.

Something like this has been done in big aquariums but at home, it would be a problem. Actually, it was a problem at full scale as well.

[herring_fish]

Have you looked at making a homemade Gyre pump? It could be external, just above the tank. With that, you could have a water flowing away over the top and back along the bottom or out along the glass and back along the rock. A big paddle wheel could make for a comparatively laminar flow with less of a chaotic look of wave action. You could tune different parts of the tank for high flow and low flow.

[karimwassef]

Is the giant baffle/paddle visible in the tank?

[karimwassef]

Re the animation above:

Animation courtesy of Dr. Dan Russell, Grad. Prog. Acoustics, Penn State.

[herring_fish]

No This would be above the tank. I didn't draw in the plumbing going from either end to the display but they would just turn straight down to the dispersion box. The laminarizing box. Boy, I like saying that.

[ericarenee]

OK..

I have been out all day doing other Life necessary things .. GRRR THAT SUCKS..

I see lots of thinking has been going on. Reading the above comments. I agree that even with the Large pistons pulling and pushing in sync the right would push water up right before mid way. and the left would pull water down causing a middle either untouched barely touched or Quite violent....

The only Solution i see in this And i think it also applies to the pump design as well the tank Body of water itself will need to be sealed..That would bring about another issue with moving water thru the sump for mechanical and gas exchange as this can not happen at the tank surface..

But at the same time. When you push say 24x24 sq x 1 inch.. Forward while pulling the same 6 feet away... it should pull the wave as a ripple .. (maybe not cause as much tension in the middle as my mind tells me.

I think a very primitive box needs to be built to scale and test some of the ideas if nothing but done by had without mechanical help... a wooden box would work......

Herring in your Diagram where is that baffle in relation to the reef ...
Having it over head like that would be good. But it would need to be two tracks far apart to allow proper light placement...or build out of very ridged material and just on say front or back to not impede on lighting.....

I could be looking at it wrong as well......

[herring_fish]

This is a separate piece of equipment. It would be well above the tank or behind it. Again, I don’t think it is a good solution, just something that will make you say Hmmmmm and then maybe move on to something that would work better.

I still think that if the cycle time isn’t longer, the energy that is required will be very high and the problems will be great.

So once again, we are trying to figure out how to only move a the cross section of the tank 1 inch per second for four seconds and then reverse that. Right? or No?

[Gorgok]

Originally Posted by ericarenee

The only Solution i see in this And i think it also applies to the pump design as well the tank Body of water itself will need to be sealed.

This may actually be the key to making this idea possible on full length without sacrificing 2/3 of the tank to do it...

If you treat the display portion as a square tube, sealed on all walls, you will eventually get laminar flow through the bulk of it (minus the rockwork). Not sure how massive the pump would need to be, or the flow, but it could be done. Then after some time running in one direction you let it settle and reverse it. Do that a few times a day for tides going in and out.

I do wonder how large it would have to be though, would the flow have to be so high as to make having anything in the tank impossible? And what sort of plumbing would it take, 6"? 10", or the same size as the tank, as in a racetrack setup.

Though a racetrack tank would be lovely for this... Could achieve tide like flow with powerheads and time i'm sure.

[karimwassef]

Gorgok, erica, I think I agree.

There are three big targets here: laminar, longitudinal, alternating.

Laminar I think we have a solution to pump in a laminar stream with the return along the same path. If left in one direction long enough with a high enough flow rate, the whole tank will eventually move in that direction (minus rock interference).

Longitudinal. This is the one I don't think works (or works yet). The incompressibility of water (especially in an open tank) means that the injected flow will push against the bulk and that water will not immediately be able to move in the same direction. It'll want to get out of the way and that will turn the longitudinal push into a transverse wave up and down. Well - two waves, one at each end. Eventually, with enough time, this should settle into a continuous flow, but not in 5 seconds.

A sealed top could force this to happen faster - acting like a pipe.
Another wild idea is to use acoustic waves. Sound is a longitudinal wave in water and an underwater acoustic source may be able to create motion that locally feels right and with phasing, could move that motion... Impact on fish and coral?? Unknown.

Alternating. After running some math, I think this is the real killer. For that much water to form laminar, longitudinal flow in 5 seconds, then switch and turn the other way for 5 seconds. All of this at 4in/s of flow... The math just doesn't work. At least not in a little rectangular tank with 10k pumps. The flow would have to be enormous to get the flow to line up that quickly throughout the length of the tank. Then to switch that fast, the transverse wave would rise feet out of the water.

Not seeing a path right now.

[karimwassef]

Originally Posted by bvnxvhj

To be clear, I don't want to set up surface waves or standing waves by pushing flow and have it bounce back from the opposite wall. I want the entire volume to shift to the left and then to the right. No waves.

So... I'm not sure who this is but you've posted twice under new names, so I'll assume you enjoy your anonymous poking at this thread.

That's fine. To be more specific - "no surface or transverse waves"

I would like whoever it is to come out and provide your perspective in a constructive and collaborative way. I won't go looking for every mistake you've made and posted to shame you, in exclusion of all the good results I'm sure you've achieved.

[herring_fish]

Don't go looking up MY stuff. I would get laught off the site.

[karimwassef]

LOL. Failure is just the path to greater knowledge.

[ericarenee]

Originally Posted by karimwassef

LOL. Failure is just the path to greater knowledge.

So Very True... If you never Fail you will never succeed


For what its worth . Here is some of what i do For a Living.. I Know all to well about Trial and Error to Find success

http://bonnieanderica.myds.me/photo/...20416c62756d73

[JamesHolt]

The 5 seconds is gonna be the kicker..
I have next week off ,,may try a few things at the house..