Plastic Beach - Traveling Water Wave Machine

[rhizotron]

Last night I cut out parts for the ripple tank mechanism. Stainless #4 machine screws will connect the spring (an RC car shock). Actuation is to be achieved with an off-center mass attached to the front of the brushless gimbal motor. I'll be pleased if this version #1 works even just a little bit.

 

[rhizotron]

A couple new update pics for the wave machine....

The plants are growing in nicely. I zip-tied a couple of additional manzanita branches into the hardscape. The paddle design is also revised and I cut an acrylic cover for the microcontroller assembly.

 

[rhizotron]

I must be the world's slowest video editor. But I finally got this thing done. Please watch if you have a couple minutes. If you like it, please like, share and comment...

 

[rhizotron]

I assembled the prototype version ripple generator. But unfortunately it's totally wrong. With this arrangement, the RC car shock would need to work as an extension spring, but positioned above the gimbal motor it is instead compression spring. Even if the motor could actuate the ripple tank tank paddle a little bit, there would be a maddening click with each stroke. I want to make this mechanism as compact as possible and I had also hoped the spring shock along with the rod + bearing would keep it aligned, but it easily yaws back and forth. So I think it will indeed require a second rod + bearing.

This was OK though just for thinking this through some more and seeing how the parts would go together.

 

[rhizotron]

Here's another fluid dynamics + physics + aquarium idea. I built a quick prototype for securing a water pump on the bottom of a glass tank with a bare impeller pointed straight up...

This achieves the same thing as many rather cheap "vortex fountains" with impellers stirring at their bases to create rotational water motion and water vortices. Spend some more and you can also find this idea combined with a water pitcher and dubious health claims about "energized" drinking water.

To incorporate into an aquarium, I'll cut that base from black HDPE, rather than white. Here it is in a rather large (almost 5 gallons) glass vase...

With free circular water movement in that cylindrical enclosure, a vortex easily develops in as much as 11" of water depth. A small aquarium setup with a few of these spinning inside would be way too energetic for fish or most other livestock as well as live plants, but I do have a couple ideas for integrating live organisms:

1. Freshwater - moss-covered rocks
2. Marine - Coralline algae and other encrusting organisms

As with the water wave machine, the vortex generation will create most of the visual interest for the setup. There is not as direct a connection between water vortices, ecosystem development and evolution as there may be with traveling water waves, although an aquarium setup like this could model tide pools and other highly energized environments with turbulent water motion.

So the idea would be to position several of these in a tank with stones covering the remaining open tank bottom. Obstructing the rotational flow with a few round lava rocks, however, severely impedes vortex generation. I had to lower the water level to within just a couple of inches of the impeller to create a vortex...

By swirling the water with my hand in the same clockwise direction, a much stronger vortex was created....

My next test will involve trying this device in a shallow rectangular tank along with a second water pump with the impeller housing in place and pushing water around horizontally to create water rotation and probably easier vortex generation.

An additional issue is the loud sucking noise and intense air bubble generation whenever a strong vortex contacts the impeller. You would not want the setup to run like this all the time, so it could instead be controlled with on/off switch and/or input voltage control

 

[rhizotron]

I did another test and this time in a small (19" X 11" X 11") rectangular tank. With a small pump up near the waterline and pushing water around clockwise, the impeller created a strong vortex in 7" of water.

The developing vortex casts this interesting dark round shadow encircled with a bright corona.

I had to lower the water to 4" deep, but I also got vortex generation with the round stones covering most of the tank bottom.

So my idea is to use stones like these planted with either aquarium Mosses (freshwater) or Coralline Algae and other encrusting organisms (marine). Here's the tank I have in mind...

https://buceplant.com/collections/u...ns-60s-10-gallon-ultra-clear-rimless-aquarium

This would make a nice broad footprint area for a stone arrangement in an enclosure of moderate size.





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[rhizotron]

I got the FOC driver in the mail and soldered the pins in place. I hope I can get this to work with that brushless motor for the ripple tank concept...

As mentioned above, I have my eye on the Ultum Nature System 60S aquarium. This tank has a cool broad + shallow (23.62" X 14.17" X 7.09") shape and I think it might work well with either the ripple tank or the vortex aquarium idea, or both. I also a concept in mind for a concrete stand and made a quick CAD sketch. This would require a very simple concrete mold with just some pieces of plywood comprising a box within a somewhat larger box and the concrete mix poured into the space between them...

 

[rhizotron]

I did it! I got this other cheap L298N brushless driver to work. I had a frustrating time because I couldn't get it to run at all with the motor, but in another venue where I asked for help a respondent pointed out that the red power indicator LED (visible in photo) was out. So the first board I tried was just a dud. I ordered a second one and it works fine. There are better brushless drivers, but this one is good enough for experimentation. Just guesstimating it looks like the max speed I can get with this mini gimbal motor is about 300rpm.

I think I'll re-prioritize the ripple tank idea again and see if I can get this to work with an updated mechanism design.

 

[rhizotron]

Took forever and I don't know if it will work yet, but I got the ripple tank mechanism almost all assembled. It still needs the electronic signal + power connections and a second piece of aluminum extrusion attached at a right angle for positioning on the wall to suspend over the tank water...

This is intended to work in a manner similar to a telegraph sounder or doorbell mechanism, with a controllable electromagnet pulling and releasing a piece of steel to create the up-and-down paddle motion. The large white bead at the end of the arm will serve as the ripple-generating paddle. Here's a better view showing the electromagnet, thick steel collar, bearings and return spring...

Reviews for this economy electromagnet described it as "weak", "loud" and "hot". But it already has its own circuit board, so it should be easy to connect for a test. If it runs at all and if I need better performance, I'll look for an upgrade or build my own later.

I'll try to get it installed this weekend to see how it goes.

 

[Ben549]

Took forever and I don't know if it will work yet, but I got the ripple tank mechanism almost all assembled. It still needs the electronic signal + power connections and a second piece of aluminum extrusion attached at a right angle for positioning on the wall to suspend over the tank water...

This is intended to work in a manner similar to a telegraph sounder or doorbell mechanism, with a controllable electromagnet pulling and releasing a piece of steel to create the up-and-down paddle motion. The large white bead at the end of the arm will serve as the ripple-generating paddle. Here's a better view showing the electromagnet, thick steel collar, bearings and return spring...

Reviews for this economy electromagnet described it as "weak", "loud" and "hot". But it already has its own circuit board, so it should be easy to connect for a test. If it runs at all and if I need better performance, I'll look for an upgrade or build my own later.

I'll try to get it installed this weekend to see how it goes.

This is an awesome idea so don't get too distracted by my feedback. Anyways, here's the feedback:
- There's no way that stepper will be able to handle salt creep. You can definitely find IPX rated steppers that will work. Even vacuum rated steppers should be all stainless steel.
- Regarding the heat of the stepper, IMO, that should be manageable. I assume you're running it at 12-24v and 1.5A or less. If you reduce that current through gearing, you can strip away the vast majority of that heat. Also, remember that steppers are rated to run pretty hot and you can even source steppers that can exceed 100C without degrading the life of them.
- one approach to gearing to consider is a simple spring tensioned rack and pinion which will offer gearing and help separate the motor from the tank.
- FOC is an interesting idea. I've mostly used the STM32 FOC using the STM tools(which are pretty good) as well as simpleFOC. The higher power density of BLDC outrunners Is interesting but heat will be a challenge since you don't have a good mechanism for cooling the motor.


IMO, an ideal approach would be putting a rail or set of rails on the inside the tank with the paddle or ball attached and then a matching rail or rails on the outside of the tank and magnetically couple the mechanisms. The paddle or ball could be designed to float so that it would pretension the mechanism.

Food for thought. This is cool, keep going.

 

[rhizotron]

This is an awesome idea so don't get too distracted by my feedback. Anyways, here's the feedback:
- There's no way that stepper will be able to handle salt creep. You can definitely find IPX rated steppers that will work. Even vacuum rated steppers should be all stainless steel.
- Regarding the heat of the stepper, IMO, that should be manageable. I assume you're running it at 12-24v and 1.5A or less. If you reduce that current through gearing, you can strip away the vast majority of that heat. Also, remember that steppers are rated to run pretty hot and you can even source steppers that can exceed 100C without degrading the life of them.
- one approach to gearing to consider is a simple spring tensioned rack and pinion which will offer gearing and help separate the motor from the tank.
- FOC is an interesting idea. I've mostly used the STM32 FOC using the STM tools(which are pretty good) as well as simpleFOC. The higher power density of BLDC outrunners Is interesting but heat will be a challenge since you don't have a good mechanism for cooling the motor.


IMO, an ideal approach would be putting a rail or set of rails on the inside the tank with the paddle or ball attached and then a matching rail or rails on the outside of the tank and magnetically couple the mechanisms. The paddle or ball could be designed to float so that it would pretension the mechanism.

Food for thought. This is cool, keep going.

Thanks for checking it out!

This is a freshwater setup, so salt creep is no issue. Even so, it's hard to imagine salt creep getting as far as the motor. It would have to progress up the carbon rods, across the follower, onto the cam, over the cam and across the motor shaft. Salt creep would become obvious if it developed on the first set of polymer linear bearings, but it would also be easy to rinse away with clean water. Salt spray could land on the stepper, but it should be easy wipe away. My idea for the version 2.0 is a brackish setup with moderate salinity in a 36" or 48" tank for mangrove plants and estuary livestock. I'll keep your stainless or waterproof stepper suggestion in mind for that.

I was concerned about stepper heat generation, but with the updates it's not bad at all. The driver does get hot, but this thing has already run at least a half million paddle strokes and the micontroller and everything seem OK.

The logic behind this design is to keep the hardware as compact as possible and all the way over at the motor end of the aquarium to leave as much space open as possible for wave generation and aquascape. I can't quite picture the mechanism you describe, but I have specifically wanted to avoid gears because they are another opportunity for introduction of noise. I intend for the updated version to run pretty much silently. I like the cam & follower very much, but I have a better mechanism involving a push rod in mind for the new setup.

I know next to nothing about brushless motors, so my plan is to just get a probably suitable BLDC motor and try to configure it to run with FOC. There is some good online support where I can ask for guidance. I'd be interested to hear if you might have specific motor suggestions. Something that can run low rpm with FOC and with torque comparable to the stepper in this machine (specifications: https://www.omc-stepperonline.com/n...in-2-1a-3-36v-42x42x60mm-4-wires-17hs24-2104s) should be a good starting point. Water-resistant would be preferable and I want to avoid a geared motor for noise and longevity concerns. A gimbal motor might work if I can figure out the linkages without a shaft (should be doable).

 

[rhizotron]

Well it was rather fussy work and took quite a while to complete, but I got the ripple mechanism updated and installed with one of my shallow 24" X 24" tanks. It still needs substrate and an aquascape, but the ripple generation seems pretty good. This is a freshwater setup. I might add a few nano fish eventually, or just leave it as kinetic water sculpture with a sparse planting. The center of the square space will remain as bare sand for the best view of the water ripples....

There is 16" of space on the 80-20 aluminum extrusion above the mechanism and I intend to build an enclosure for the micro controller to position there.

I like how some of the finish details turned out ...

The spring (an RC car shock) at the rear is stiff in comparison to the electromagnet pulling strength, but the elastic band provides opposing force. Both are adjustable...

I also uploaded a quick Instagram video clip which should be viewable if you have a login...

https://www.instagram.com/reel/CurLHJRgJyp/?utm_source=ig_web_copy_link&igshid=MzRlODBiNWFlZA==

 

[rhizotron]

Ripple tank update!

Quick Instagram reel...




It took me all night, but I got the sand, aquascape and plants into the setup. The Cryptocoryne lucens had melted back with a couple of moves between tanks, but the foliage is starting to resprout. I also put together the little in-tank filter design I've been pondering.

After the setup has matured for a while, I'll probably add some nano fish. Most likely a small group of Tanichthys albonubes...

 

[Gumbies R Us]

Ripple tank update!

Quick Instagram reel...




It took me all night, but I got the sand, aquascape and plants into the setup. The Cryptocoryne lucens had melted back with a couple of moves between tanks, but the foliage is starting to resprout. I also put together the little in-tank filter design I've been pondering.

After the setup has matured for a while, I'll probably add some nano fish. Most likely a small group of Tanichthys albonubes...

That ripple generator you made looks like it works great! Can't imagine the time and effort it took into making that.

 

[BeanAnimal]

so technical and amazing, wow

I don't recall seeing things like that on forums very often at all/ever

If you are interested there is a lengthy RC thread from 15 years ago where numerous designs were discussed. Everything from paddles (like the wave design in this thread) to large volume push pull pistons or float boxes, air bladders, boat props, etc. Paul from oceans motions even built a prototype of a large volume oscillating valve. Nobody other than Paul actually built anything…

The wave design in this thread is what Is used in most wave pools.

The OP has done a wonderful job with the research, iterative design improvements and implementation. Great thread And amazing work throughout.

 

[rhizotron]

That ripple generator you made looks like it works great! Can't imagine the time and effort it took into making that.

Thanks so much! Yes it's a simple mechanism, but somehow it took forever to finish the final assembly...fussy work. Seems to be running OK though. I'm eager to get the Kessil hung up because that will create much clearer shadows and reflections to show the ripple physics.

If you are interested there is a lengthy RC thread from 15 years ago where numerous designs were discussed. Everything from paddles (like the wave design in this thread) to large volume push pull pistons or float boxes, air bladders, boat props, etc. Paul from oceans motions even built a prototype of a large volume oscillating valve. Nobody other than Paul actually built anything…

The wave design in this thread is what Is used in most wave pools.

The OP has done a wonderful job with the research, iterative design improvements and implementation. Great thread And amazing work throughout.

Thanks for following along! I would be interested to see that. Can you suggest any other search terms to use? I went looking but couldn't find it. I have several more ideas for "anything but impeller" water motion and updates for these designs I have here.

I've wondered about pneumatic cylinder paddle actuation with a mini airbrush air compressor. because that would be a pretty cool mechanism and also mechanically durable. But the likely loud noise, both from the compressor motor and the cylinder exhaust, is an issue.

 

[BeanAnimal]

Thanks for following along! I would be interested to see that. Can you suggest any other search terms to use? I went looking but couldn't find it. I have several more ideas for "anything but impeller" water motion and updates for these designs I have here.

I've wondered about pneumatic cylinder paddle actuation with a mini airbrush air compressor. because that would be a pretty cool mechanism and also mechanically durable. But the likely loud noise, both from the compressor motor and the cylinder exhaust, is an issue.

I will see if I can dig it up. It may be archived and not searchable in the old forum format.

One of the simplest designs was a large diameter tube (say 8" or 10" or more) in close proximity to the tank with a simple reciprocating piston. Intake and exhaust through the same port with a diffuser panel in the tank. Push pull like the tide.

The next thought was to have the two opposed ports, one on either end of the tank. It would would move twice the water for the same stroke and create a more laminar flow.

Or sectioned off boxes at either end of the tank with large slots at the bottom and piston blocks moving in opposing motion, pushing and pulling water end to end in the tank.

The piston would not have to be a tight fit in most cases.

We discussed many means of powering such devices One we did not discuss though would be hydraulically with a pump and tank water.

The boat propeller or trolling motor idea was similar. Basically a large diameter 8 " - 10" closed loop with one (or two opposed) that could move large volume of low pressure water intermittently in one or both directions.

We also discussed numerous adaptations of carlson surge devices, reverse carlson surge devices, large bell siphons, etc.

Of course most of this is not space friendly or aesthetically pleasing.

I want to again commend you on the research, ingenuity and craftsmanship presented here.

 

[rhizotron]

I will see if I can dig it up. It may be archived and not searchable in the old forum format.

One of the simplest designs was a large diameter tube (say 8" or 10" or more) in close proximity to the tank with a simple reciprocating piston. Intake and exhaust through the same port with a diffuser panel in the tank. Push pull like the tide.

The next thought was to have the two opposed ports, one on either end of the tank. It would would move twice the water for the same stroke and create a more laminar flow.

Or sectioned off boxes at either end of the tank with large slots at the bottom and piston blocks moving in opposing motion, pushing and pulling water end to end in the tank.

The piston would not have to be a tight fit in most cases.

We discussed many means of powering such devices One we did not discuss though would be hydraulically with a pump and tank water.

The boat propeller or trolling motor idea was similar. Basically a large diameter 8 " - 10" closed loop with one (or two opposed) that could move large volume of low pressure water intermittently in one or both directions.

We also discussed numerous adaptations of carlson surge devices, reverse carlson surge devices, large bell siphons, etc.

Of course most of this is not space friendly or aesthetically pleasing.

I want to again commend you on the research, ingenuity and craftsmanship presented here.

Thanks again for stopping by.

I have another concept in mind incorporating a bell siphon controlled with timed water pumping to simulate tidal water level changes. This would in turn support aquarium stromatolite development as a model ecosystem based on the thrombolite (microbially-formed structures similar to stromatolites) of Highborne Cay, Bahamas...

A Study of the Microbial Spatial Heterogeneity of Bahamian Thrombolites Using Molecular, Biochemical, and Stable Isotope Analyses May 2017 Astrobiology 15(5):413 DOI:10.1089/ast.2016.1563

So it would resemble the stromatolite tank I already have going, but with the feature top surfaces and their microbial mat ecosystems exposed during the simulated low tide period...

While this stromatolite setup is hypersaline (85ppt) the new tank would hold either marine salinity or brackish water. Since the microbial mat top surfaces would be either exposed at low tide or under very shallow water, they will be protected from grazers, so I could also add fish to the tank.

I also have the aesthetics and visual coherence in mind. I think that a simple round cylinder (4" or 6" pipe section) as the bell siphon container hung on the wall and centered over the tank will look pretty good. I can also finish it with a coat of paint and other details.

 

[BeanAnimal]

Thanks again for stopping by.

I have another concept in mind incorporating a bell siphon controlled with timed water pumping to simulate tidal water level changes. This would in turn support aquarium stromatolite development as a model ecosystem based on the thrombolite (microbially-formed structures similar to stromatolites) of Highborne Cay, Bahamas...

A Study of the Microbial Spatial Heterogeneity of Bahamian Thrombolites Using Molecular, Biochemical, and Stable Isotope Analyses May 2017 Astrobiology 15(5):413 DOI:10.1089/ast.2016.1563

So it would resemble the stromatolite tank I already have going, but with the feature top surfaces and their microbial mat ecosystems exposed during the simulated low tide period...

While this stromatolite setup is hypersaline (85ppt) the new tank would hold either marine salinity or brackish water. Since the microbial mat top surfaces would be either exposed at low tide or under very shallow water, they will be protected from grazers, so I could also add fish to the tank.

I also have the aesthetics and visual coherence in mind. I think that a simple round cylinder (4" or 6" pipe section) as the bell siphon container hung on the wall and centered over the tank will look pretty good. I can also finish it with a coat of paint and other details.

The Carnegie Science Center here in Pittsburgh used to have a tidal lagoon tank that utilized a large dump bucket to simulate wave action. I as neat, but took a good bit of maintenance from what I remember.

 

[rhizotron]

The Carnegie Science Center here in Pittsburgh used to have a tidal lagoon tank that utilized a large dump bucket to simulate wave action. I as neat, but took a good bit of maintenance from what I remember.

Another variation I had in mind was just a return outlet with solenoid in place of the bell siphon apparatus. Either option would also require an overflow with a flexible line near the top of the tube enclosure in case of solenoid or siphon failure.

A rather sad story, but I just ran into this thing about the Cuatro Cienegas pools in Mexico. I had heard about the unique Cichlids and other fish in these habitats, but was not aware they also have/have had such well-defined stromatolites. In most places it's politically impossible to do much about groundwater extraction and in this case these really unique desert oasis features are drying up...

https://www.nature.com/articles/d41...ONol21GklPbwLNCl1vYng2QZCeFc82T5ZwoNPCKKyfcQA

I really need to research some more to figure out the basics of stromatolite formation in freshwater. Another really cool example are the microbial features of Green Lake, New York...

https://ottohmuller.com/nysga2ge/Fi... lake, Green Lake, Fayetteville, New York.pdf