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Re: science guys! ... new idea - world's fastest bottles [lacticturkey] [ In reply to ]
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It seems to me that any losses due to water movement in the bottle are going to come from shear resulting from the flow. So, there'll be some kinetic energy lost as heat due to liquid movement. It's not going to be very large IMO and it'll be rather difficult to estimate. Flows in an agitated bottle are going to be highly turbulent and entirely dependent on liquid properties, bottle size, shape and surface, bottle orientation and location on the bike, and exact motion of the bike. When your cadence changes, the frequency of the motion will change. When power or your position or the gradient, or wind changes, the amplitude and orientation of motion will change. As the volume of water in the bottle changes, everything changes. Far too many variables and any solution would be based on a myriad of questionable assumptions, making it worthless. The problem is an absurd one for which to attempt to produce a figure by calculation.

Now, if you put in a baffle, you can reduce the range of motion of the fluid. But how will that reduce energy loss?
In order for a baffle to prevent motion it must produce resistance. You can change the size, location and orientation of flows within the body of liquid, but you can't eliminate liquid movement. The same volume of liquid will remain in motion. What makes you think the baffle will reduce the losses due to that movement?
It's not a very intuitive problem! It's not immediately obvious whether a baffle will increase or reduce energy loss, but I'm pretty sure it'll increase it: see below.

You've described your proposal as a "wave breaker". Waves move potential and kinetic energy about incredibly effectively. To "break" the wave you would be introducing turbulence to mix the flow and damp the wave. Therefore wouldn't the breaker actually be the means of converting the energy from a useful form into heat more effectively than a simple bottle would ever achieve? And that's the opposite of what you want.

If it helps, consider a fluid trainer. The resistance is not created by moving a wave around. It is created by generating turbulence, i.e. lots of fluid shear in the resistance unit, and this creates heat which is dissipated into the ambient air through the body of the resistance unit. A bottle with baffles would do essentially the same thing by creating small scale turbulence that effectively converts kinetic energy to heat. I believe it would make things considerably WORSE not better than a standard bottle.

As others have pointed out, the comparisons made in some posts to rocket and motor vehicle fuel tank baffles are missing the point. Those are used to control the liquid to allow reliable access and to maintain control and stability. It's not about efficiency.
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Re: science guys! ... new idea - world's fastest bottles [JasoninHalifax] [ In reply to ]
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JasoninHalifax wrote:
awenborn wrote:
lacticturkey wrote:
Without science it's hard to estimate the energy savings.


As you and others have mentioned, it shouldn't be too hard for someone with the requisite skills to model. I'd be surprised if it's a significant amount, even if you're crit racing with lots of cornering and accelerations.

Also, with respect to motorsport, one of the key reasons for fuel tank/oil sump baffles is to make sure that during periods of sustained sideways g-force (e.g. long corners) that all the fuel/oil doesn't slosh to one side of the tank, away from the feed pipe and starve the engine of fuel/oil. Obviously this isn't a concern in water bottles.


I thought the OP was joking. Now, not so sure.

If there are energy losses from the water sloshing, then the baffle will increase the amount of energy dissipated (that's what baffles do) and make you slower. In theory anyway.
Yep, this^^^^^

I started writing my last post, went away for a while, came back and posted it only to find three other posts had appeared in the mean time addressing exactly the same points.
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Re: science guys! ... new idea - world's fastest bottles [Ai_1] [ In reply to ]
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Do bottom line is ... Fluid moving in a space won't dissapate more than the same volume of fluid spread across 5 small compartments

I thought that the overall energy would be less when not giving the fluid enough space to create waves but can see that this energy would just be spread not reduced

Would've been great if waveless bottles made your bike feel less sluggish

Kind of on the same principle as compression clothing reducing muscle rebound in sprinting....
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Re: science guys! ... new idea - world's fastest bottles [lacticturkey] [ In reply to ]
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lacticturkey wrote:
Do bottom line is ... Fluid moving in a space won't dissapate more than the same volume of fluid spread across 5 small compartments

I thought that the overall energy would be less when not giving the fluid enough space to create waves but can see that this energy would just be spread not reduced

Would've been great if waveless bottles made your bike feel less sluggish

Kind of on the same principle as compression clothing reducing muscle rebound in sprinting....
If the bottle is moving the same motion is being imparted to the fluid regardless. The movement of the liquid in the bottle in response to that motion is actually the very thing it sounds like you are trying to achieve - the water is "trying" NOT to accelerate. So if we just look at the longitudinal axis for simplicity and take a bike that is surging and slowing between pedal strokes: As the bike surges forward, the water tends to maintain it's existing velocity and accumulates at the end of the bottle closest to the back of the bike. The water is sloshing relative to the bike but it would be more useful perhaps to consider the bike agitating the water. It is reduction of the accelerations imparted by the bike that best allow you reduce energy loses. So ideally perhaps you would isolate the bottle from bike accelerations by allowing the bottle to continue moving at a mean rate as the bike surges and sways around it. But I doubt you can come up with a practical and worthwhile way to do that!
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Re: science guys! ... new idea - world's fastest bottles [Ai_1] [ In reply to ]
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Interesting explanation!

So then a suspended BTA bottle setup could save energy by allowing the bottle to float independantly ...like neoprene hammock or springs instead of tiewraps ?
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Re: science guys! ... new idea - world's fastest bottles [lacticturkey] [ In reply to ]
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#notcarbon
#notgoingtoselltorichagegrouperwithtoomuchmoney
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Re: science guys! ... new idea - world's fastest bottles [lacticturkey] [ In reply to ]
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lacticturkey wrote:
Interesting explanation!

So then a suspended BTA bottle setup could save energy by allowing the bottle to float independantly ...like neoprene hammock or springs instead of tiewraps ?

In theory, yes. But, in practice such a suspension system would need to be damped to prevent harmonic oscillations from being imparted to the suspended bottle---that dampening will just be absorbing energy, again. It would also need to be "loosely sprung", with a large range of motion to allow the bike to move without imparting too much force to the bottle. I think that's probably a loosing battle.
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Re: science guys! ... new idea - world's fastest bottles [lacticturkey] [ In reply to ]
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Personally I think that this is a really interesting idea.

There is little doubt that a conventional bike water bottle has a lot more fluid movement than a fully baffled bottle. And even more so when the bottle is not 100% full (which is most of the time). When the fluid sloshes back and forth, it does indeed 'steal' energy. An easy demo of this is a classic egg trick. When put on a smooth flat table, a raw egg is very difficult to spin and, once spun up, it slows down very very quickly. Not so with a hard boiled egg of exactly the same mass, it will spin easily and for a long time.

Heck, you can also really see this on a bike with a vertical aerobar bottle. Without a baffle, the liquid in any of the bottle designs sloshes like CRAZY. But, add a splash-reducing sponge, and you don't even need a lid on the bottle, the sloshing is reduced easy by 95% plus.

But, of course, the devil is in the details. How much energy does a couple of unbaffled water bottles on a bike really suck up?

If the energy loss is non-trivial (and, admittedly, that is a big 'if'), I think one would have to use a full foam insert in the bottles (vs just plastic baffle louvers as pictured above) to really reduce fluid sloshing significantly. Or at least that is my armchair quarterback opinion ... :^)

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Re: science guys! ... new idea - world's fastest bottles [Tom_hampton] [ In reply to ]
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Tom_hampton wrote:
lacticturkey wrote:
Interesting explanation!

So then a suspended BTA bottle setup could save energy by allowing the bottle to float independantly ...like neoprene hammock or springs instead of tiewraps ?


In theory, yes. But, in practice such a suspension system would need to be damped to prevent harmonic oscillations from being imparted to the suspended bottle---that dampening will just be absorbing energy, again. It would also need to be "loosely sprung", with a large range of motion to allow the bike to move without imparting too much force to the bottle. I think that's probably a loosing battle.
Exactly. It's not a practical proposal. A simple spring won't cut it and as Tom says, the range of motion needed is significant. We're not talking 5mm of give in the bottle cage. More like an articulated cradle. It ain't a runner!
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Re: science guys! ... new idea - world's fastest bottles [DarkSpeedWorks] [ In reply to ]
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DarkSpeedWorks wrote:
Personally I think that this is a really interesting idea.

There is little doubt that a conventional bike water bottle has a lot more fluid movement than a fully baffled bottle. And even more so when the bottle is not 100% full (which is most of the time). When the fluid sloshes back and forth, it does indeed 'steal' energy. An easy demo of this is a classic egg trick. When put on a smooth flat table, a raw egg is very difficult to spin and, once spun up, it slows down very very quickly. Not so with a hard boiled egg of exactly the same mass, it will spin easily and for a long time.

That's pretty poor example. The material properties of raw egg white are hardly the same as cooked. The cooked egg white has become bonded molecularly (ok, entangled might be a better term). But, the material is no longer fluid, and energy can be directly transferred from molecule to molecule...much more like a crystalline structure.

In the baffled case every little compartment is still filled with FLUID, which still moves in a loosely coupled manner. But, as Ai_1 points out...the sloshing itself is not the enemy. Its the halting of the sloshing via friction (internal sheer, and with the walls of the container/baffles). I'm sure there is a calculus to it, though. As you describe, if I subdivide the fluid fine enough (using open celled foam?), perhaps I get ahead of the game and less energy is imparted into the fluid in the first place.

But, those dividers take up space, and have mass of their own. How far to do I have to subdivide to start making ground on the energy loss? And how much mass/volume do the dividers take up, such that now I have to make my bottle larger in order to hold the same amount of fluid? At which point, now I may be trading aero energy loss.

If I were going to even consider pursuing this, I think I'd do some testing to find out how much actual energy loss we're talking about. Two bottles equal mass, one filled with water, one filled with solid resin or something. Dunno if Chunging would be sensitive enough, but it'd be worth a shot. If not, that's probably an answer right there.
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Re: science guys! ... new idea - world's fastest bottles [lacticturkey] [ In reply to ]
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In the realm of tri products that provide marginal (or better yet unproven) gains at an exorbitant cost, baffles in a water bottle sound great. Ceramic Speed Works sells their OSPW system for about $500. You save 1 watt/$250. If this baffle might save 0.2 watts, $20 is perfectly reasonable for people to take a flyer on. It might work or it might not, but for $20, they can try it themselves.

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Re: science guys! ... new idea - world's fastest bottles [Tom_hampton] [ In reply to ]
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Of course, I fully understand that a cooked egg is not the same as a raw egg. I was just using that as an general example because, the smaller and smaller the baffles, the closer to an effective solid the liquid water will become (only an approximation, of course). I don't know how much one would have to subdivide a water bottle to get 95% of more of the liquid to stay stationary, but I imagine that it would be a lot, that is why I mention using foam as baffling vs just using a few plastic louvers.

But I can say that, watching a vertical aerobar water bottle both with an internal foam baffle and then the same bottle with nothing, the visual difference between the two is enormous in terms of liquid movement.

Is the energy savings very much? Who knows?
But that is for testing to decide.

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Last edited by: DarkSpeedWorks: Dec 14, 17 9:39
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Re: science guys! ... new idea - world's fastest bottles [Vincible] [ In reply to ]
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As long as we're in this weird twilight zone of not knowing how serious OP is, how about bottles with internal bladders?

And you could even build something like that directly into the frame of a bike...certainly no one's thought of that!

Eliot
blog thing - strava thing
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Re: science guys! ... new idea - world's fastest bottles [DarkSpeedWorks] [ In reply to ]
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I think a simple test will (dis)prove this rather rapidly. Take 2 identical bottles. Fill them both with the same amount of water. Freeze one.
test 1: ride w/ the bottle full of liquid
test 2: ride w/ the bottle full of ice.

I can save you the hassle. There's not a difference large enough to even discuss here. However, as so many have pointed out, still may be worth making and selling as people will buy anything. Please check my site below and buy a few hologram bracelets from me. They have really improved my racing this year!

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Re: science guys! ... new idea - world's fastest bottles [mkerley] [ In reply to ]
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mkerley wrote:
I think a simple test will (dis)prove this rather rapidly. Take 2 identical bottles. Fill them both with the same amount of water. Freeze one.
test 1: ride w/ the bottle full of liquid
test 2: ride w/ the bottle full of ice.

I can save you the hassle. There's not a difference large enough to even discuss here. However, as so many have pointed out, still may be worth making and selling as people will buy anything. Please check my site below and buy a few hologram bracelets from me. They have really improved my racing this year!

Find the marketers of Halo they would be all over this...
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Re: science guys! ... new idea - world's fastest bottles [mkerley] [ In reply to ]
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making fluid sway inside 2 or 3 bottles with fluid swaying constantly for 5 hours cant be nothing


the baffles would also have to work vertically so there might need to be fins like this - to create smaller compartments but that still dont block flow for emptying or filling and also dont take up space inside the bottle like a sponge...


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Re: science guys! ... new idea - world's fastest bottles [renorider] [ In reply to ]
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that reminds me of the elastic drink bladder with bite valve from the 90s - called the airstream or jest stream or something .... youre right in that an elastic capsule like that could contain wave formation



edited to add.... it was called bikestream


Last edited by: lacticturkey: Dec 14, 17 14:39
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Re: science guys! ... new idea - world's fastest bottles [lacticturkey] [ In reply to ]
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It is essentially nothing bc your linear accelerations are so slight across that time that the forward and backward movement of the water has nearly no effect on your inertia. But like I said, the test is really simple. The frozen water is effectively perfectly baffled. You’d be much better off to just get some lighter shoestrings or cut some of the unused Velcro off your shoes. Seriously.

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Re: science guys! ... new idea - world's fastest bottles [lacticturkey] [ In reply to ]
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lacticturkey wrote:
making fluid sway inside 2 or 3 bottles with fluid swaying constantly for 5 hours cant be nothing

Its not, but it might be damn near. let me ask it this way:

if we insulated your water bottle with a giant vacuum flask so that no heat could enter the bottle or escape from it, then all that heat would have to warm up the liquid inside the bottle. How much do you think 32oz liquid would heat up after 1 hour of sloshing on the bike? 1 degree, 10 degrees, 50 degrees?



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A little physics:

32oz = 896 grams (or CCs)
It takes 1 Calorie per gram to raise the temperature of water 1 degree C.
1 watt = 0.24 Cal per second
3600 sec = 1hour

So, it takes 896 calories to raise the temperature of that bottle by 1 degC. Lets say that happens in an hour. 896 cal / 3600 sec = 0.2489 cal/sec or roughly 1 watt.

Therefore, if the water is absorbing 1 watt continuously for an hour it should be 1 degC (or 1.8 F) warmer after an hour (assuming it is well insulated). Does that seem reasonable? Maybe...hard to say really.

That's kinda convenient, because it makes other cases pretty simple to consider. 10 watts would mean it would be 10C or 18F warmer. I think that's clearly preposterous. Even if I put a water bottle on a paint shaker for an hour, I'd be SHOCKED if it was almost 20 degrees warmer afterwards (70F => 90F). I shouldn't even need insulation to detect this amount of heating.

My guess is that it is somewhere well below 1 watt.
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Re: science guys! ... new idea - world's fastest bottles [lacticturkey] [ In reply to ]
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not a lot of acceleration/deceleration in long course tri, which would seem to be the primary targeted use for this.
maybe send it over to team cambell soup rebels.

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Re: science guys! ... new idea - world's fastest bottles [lacticturkey] [ In reply to ]
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I bet the Ventum reservoir could benefit from fuel cell like foam..... However I bet for my long runs I would be more likely to carry a bottle if it did not bounce around as much. Perhaps the better application is for runners....
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Re: science guys! ... new idea - world's fastest bottles [scca_ita] [ In reply to ]
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scca_ita wrote:
I bet the Ventum reservoir could benefit from fuel cell like foam..... However I bet for my long runs I would be more likely to carry a bottle if it did not bounce around as much. Perhaps the better application is for runners....
The ventum resevoir might benefit in terms of eliminating any off putting harmonics but it's questionable if it would otherwise impact performance.
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Re: science guys! ... new idea - world's fastest bottles [Ai_1] [ In reply to ]
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With running the forces are in more oscillating directions.... I can imagine that baffled water might make the bottle bounce more. With biking force being in a constant direction the thought was keeping water going in the same direction too somehow.

For running I imagine a vest with 4 compartments could help...like a camelback but spread left/right and front/back with a communicating tube at top ... So that forces are only applied to a small segment of water at a time during each phase of running step

Example...you would have quarter of the fluid on the side of the leg during footstrike

Do motorbike tanks have baffles?
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Re: science guys! ... new idea - world's fastest bottles [scca_ita] [ In reply to ]
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scca_ita wrote:
I bet the Ventum reservoir could benefit from fuel cell like foam..... However I bet for my long runs I would be more likely to carry a bottle if it did not bounce around as much. Perhaps the better application is for runners....

When I've tried carrying a bottle on a belt, for example, it was the weight I noticed, not the sloshing. i.e. it was most annoying and noticeable when the bottle is completely full (no sloshing if its full). if the bottle was half full it bounced far less, even though the liquid inside sloshed around a lot more.

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Re: science guys! ... new idea - world's fastest bottles [lacticturkey] [ In reply to ]
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lacticturkey wrote:
With running the forces are in more oscillating directions.... I can imagine that baffled water might make the bottle bounce more. With biking force being in a constant direction the thought was keeping water going in the same direction too somehow.

For running I imagine a vest with 4 compartments could help...like a camelback but spread left/right and front/back with a communicating tube at top ... So that forces are only applied to a small segment of water at a time during each phase of running step

Example...you would have quarter of the fluid on the side of the leg during footstrike

Do motorbike tanks have baffles?
Baffles serve a purpose - control of liquid movement. I don't contest that.
It's useful/necessary for many reasons and would probably be helpful in running hydration applications. But there are 3 different topics being continually mixed together throughout this thread and it's not useful.
  1. Trying to use fluid motion reduction within a vessel to reduce energy loses
  2. Control of liquid movement to maintain proximity to pick up tube for vehicle fuel or hydration purposes
  3. Control of liquid movement to control mass distribution changes for dealing with handling, harmonics and comfort issues

It seems to me that you're thinking about a solution and looking for corresponding problems. That's not generally a useful approach unless you have a product and you're trying to figure out a way to sell it. From an engineering approach, you typically start with a problem and look for a solution.
Regardless, I'd suggest disentangling the potential problems you want to address. Whether a baffle is used in a motorbike is not useful in deciding whether you want one on your bike unless you know WHY it is or is not on the motorbike.

I see zero point in talking about fuel tanks on motorbikes if you want to know about bicycle drink containers:
  • Large volume of fuel stored high up on a motorbike, thus might be potential dangerous handling issues - not an issue for a bicycle
  • Tank rigidly attached to the vehicle and needs to provide a constant flow of fuel - not applicable on a bicycle: you hold the bottle in your hand to drink or in the case of a BTA bottle, you use it while velocity is pretty constant.


May I ask - What specifically is the purpose of this topic at this point? I'm getting lost.
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