A Lagit question on a Bakki Shower Installation

[poey]

hi

i have run 60kg of media in a 3 tier shower on the old pond,because the shower was stood on the pond side and if i stacked it 4 tiers it stuck above the fence .
i now run the same 60kg in a four tier shower along with a double unit.i figure the degassing effect will be greater when running the same amount of media in 4 tiers instead of 3?
cheers Dave.

[James P]

why so sensitive? We're just talking about water flow for heaven's sake? I think Luke has it right in that flow from one section to another is a separate event. The height would only allow for longer degassing time intervals and more exposure of water sheets to wetted surfaces ( based on number of trays).
You all can try this- I knocked out the bottoms of four five gallon aquariums and replaced the bottoms with egg crate ( the material used as light lens in suspended ceilings) These fish tanks are now stacked over a rubbermaid stock tank. I have experimented with several size pumps. In all cases, at least to the naked eye, the 'shower' portions look to be equal in volume and intensity between tanks sections. Because the aquariums are clear you can see the 'action' in the media. In all four tanks the dwelling of water is nil- that is-- the same. I would suggest that if velocity was increasing, you would notice some accumulation or congestion in the lower trays- or possibly a noticable intensity between trays?

[dick benbow]

As I Read This Thread...

[dick benbow]

As I Read This Thread...

I couldn't help but think that perhaps we have something akin to filtration
in series or independent.

iN THIS CASE WITH THE SHOWER WE HAVE SOMETHING IN SERIES...


I run both J-mat and BS in " series "

[Valarc]

I gotta disagree with you there JR. Unless the media was already at its maximum capacity for handling flow, the extra velocity probably wouldn't cause any visible congestion. There is a CHANCE there could be some acceleration happening there... but as my calculations already showed, even under "ideal" circumstances it's very little. Definitely too little to see the difference with the naked eye. I would think the most likely visual cue of a change in velocity would be the amount of splashing. If the water is falling faster, it should splash more and higher in the lowest tray compared to the second from the top (not the top, so we're still comparing the same distribution of water). However, whether this is a large enough effect to be noticable is questionable.

I have my doubts as to whether there's any actual velocity difference or not. It all depends on the dwell time of the water within the individual shower sections, which I guess you could get some handle on by turning the shower off and seeing how long it takes to stop flowing.

As a physics guy, I love this discussion because it's getting people thinking critically about what's really happening to the flow here. I propose a little thought experiment just to get our noodles cranking. Imagine water flowing in a thin sheet down a flight of stairs. When water falls from one stair to another, it splashes and changes direction. In the middle of the stair, all of the energy obtained from that fall is now pushing the water horizontally. When the water goes over the edge to the next stair, there's no reason for that horizontal motion to change direction, so the energy of the fall to the next stair comes only from the current height, and not the previous height of the staircase. Therefore, the speed when it hits the bottom of the next stair is THE SAME as what happened on the previous stair. No matter how many stairs you stack up, the velocity at the bottom of a given stair will be the same.

The question then becomes, does the BHM act like the set of stairs, or do the curved surfaces allow the water to always maintain a bit of its vertical velocity and hence increase due to acceleration? Unfortunately, this is an incredibly complex question and answering it would probably be a calculation worthy of publication It IS fun to speculate, though.

[Valarc]

Quote: Originally Posted by junglegeorge12 Since the flow rate feeding it does not slow up, you have a small accummulation or buildup, then this little thing called weight and gravity take over and the water accelerates simply based on accumulation and weight. Any equations that apply would have to factor in water weight, flow rates per sq/in. and resistance to downward flow the media causes. That is why a taller tower with less surface area per gallon/min. of flow rate would enhance acceleration. More buildup of weight more quickly.

George if there were any buildup capable of sustaining weight, the showers would back up and overflow, or as JR said he would see it in his clear showers as he went lower. Neither is the case, so accumulated weight doesn't factor in. As I said, my calculation showed the FASTEST POSSIBLE velocity one could find at the bottom. This is based solely on the amount of energy available. There is NO OTHER SOURCE of energy here, and so the ONLY possibility is for it to go SLOWER than what I calculated, which is what I said from the beginning. Unless you're maybe suggesting FIR causes the water to speed up too?

Your little jab at classroom science was pointless and added nothing to the discussion - I never claimed to be calculating the actual velocity, but rather the upper limit on it. Quit trying to put words into my mouth and make it sound like I claimed something I didn't. This BS in your discussions is why it always turns into a fight when you stick your nose in.

[Valarc]

Quote: Originally Posted by gregbickal What happend to Newton and the apple? I thought that if you dropped an apple and a bowling ball from the same height that they both hit the ground at the same time?

The apple and bowling ball aren't going through a complex maze of curvy ceramics bouncing them this way and that.

But actually, if you go back and look at my velocity calculations, you'll see that I cancelled out the mass in the calculation of final velocity. That is, the final velocity depended only on the height, and NOT the mass!

As far as the skydiver thing.. as others have pointed out, at those speeds air resistance plays an important role. Roughly speaking, air resistance goes as the square of velocity. That is, it grows exponentially with increasing velocity. That's why at low speeds we don't really notice air resistance, but at high speeds it's a HUGE effect.

[Koi Story]

Quote: Originally Posted by gregbickal What happend to Newton and the apple? I thought that if you dropped an apple and a bowling ball from the same height that they both hit the ground at the same time?

That is correct Greg, not the apple but
Galileo’s Balls

MORE than 400 years ago Galileo reputedly dropped a cannonball and an identical bowling ball from the Leaning Tower of Pisa. Galileo showed that the two balls would land at the same time, despite having different masses. This understanding eventually led to Einstein's equivalence principle*, which underlies the general theory of relativity.

This principle has already been tested in Earth-based experiments to an accuracy of one part in a trillion. A space-based experiment, called MICROSCOPE was launched by ESA in 2004 to test this principle; its expected to be about a thousand times more accurate.

ks

[kingkong]

Newton's first law of motion declares that a force is not needed to keep an object in motion. Falling water is interrupted and slows by the presence of a force hitting objects (BS), the force of friction. Without the BS, the water would continue in motion with the same speed and direction forever or until hitting an equal force upwards like water.

[Valarc]

Quote: Originally Posted by kingkong Newton's first law of motion declares that a force is not needed to keep an object in motion. Falling water is interrupted and slows by the presence of a force hitting objects (BS), the force of friction. Without the BS, the water would continue in motion with the same speed and direction forever or until hitting an equal force upwards like water.

You were correct until your last sentence, kong

You forgot about the force of gravity, which is a constant pull on the water. Without BS the water would continue to accelerate at 9.8 m/s^2