# is the Coriolis Effect a mathematical principle?

Is the Coriolis Effect a mathematical principle or a different sort of principle?

(I’m thinking it has something to do with Gravity so should be called something else?)

Given it is a result of inertia in a rotating system the term “Effect” is reasonable. Described by Gustave-Gaspard Coriolis, the name is similarly so. OTOH, given it is a pseudo-force, you could reasonably call it the Coriolis Force. However “force” is the result of the “effect” when applied in a system. So the names are not equivalent. There is a lot of hair splitting possible.

Depends what you call a “mathematical principle”. It can be derived mathematically from the basic laws of motion. However it isn’t something specific to an abstract mathematical notion, but rather quite clearly something that derives from a mathematical treatment of physical laws. In that respect you are probably best off calling it a physical principle.

The only physics involved is the definitions of position, velocity, and acceleration. Everything else is just the direct result of a particularly messy coordinate transformation.

Sorry i need to be clearer.

In writing about the Coriolis effect / principle should i refer to it as
The mathematical principle of the coriolis effect
Or
The geophysical principle…
Or something else?

I am introducing mass flow metres which use the coriolis force to measure mass of bunker fuel…
Just wanna make sure i get the branch of science it comes from correct

Fluid Mechanics … be careful how you use Coriolis force …

The Coriolis force is much more general than geophysics (i.e. it is a feature of rotating frames even far away from the earth). I assume the rotating frame you are measuring Coriolis force in is the Earth’s frame (rather than having some other spinning apparatus)?

The effect is due to conservation of momentum, so I’d just call it a physical principle.

The frame is the meter itself, we’re adding a vibration to the system which mimics a rotating frame.

I’m not sure exactly what you’re trying to describe, but I have a strong suspicion that Coriolis Effect isn’t the best description. Are you sure ‘centripetal force’ or ‘centrifugal force’ isn’t the best description?

And a vibration can’t really mimic a rotating frame, either.

I found this site which seems to be similar to what we are talking about.

And I guess this.

The literature all talks about coriolis effect.

I wll mention it as

A principle from fluid mechanics known as the Coriolis Effect…
Sorted thanks dopers

The Coriolis effect is certainly not a principle from fluid mechanics, and it probably also isn’t what your device is using. What you’re planning on saying is just wrong.

Well, I learned something today: Coriolis mass flow meter.

Aren’t those a gas, we have them here for our water meters … they transmit the data so the meter reader just needs to drive by.

There is definitely a device called a Coriolis mass flow meter, and there are youtube videos by manufacturers claiming the Coriolis effect is involved (example).

I am having a bit of trouble wrapping my head around how the Coriolis effect applies in the hose example in that video, though. What’s the relevant rotating frame there? Is it the one in which the water flowing though the hose is at rest as it goes around the curved part of the hose (i.e. its axis of rotation is orthogonal to the hose) or is it the one that the hose is instantaneously in as you swing it back and forth (i.e. its axis of rotation is parallel to the a line connecting the hose-swinger’s two hands)?

I think if we model it the latter way (i.e. imagine that instead of swinging the hose back and forth, he has the hose do a full rotation, implying a rotating frame around the left-hand/right-hand axis), then at his left hand and right hand, the velocity of the water is perpendicular to the frame’s axis of rotation (and in the opposite direction). So the Coriolis term of Ω × v is orthogonal to both and opposite direction at each hand, making the twisting that this thing seems to rely on.

In the middle, the velocity of the flow is parallel to the axis, so the Coriolis term is zero.

Very cool device.

Would make the point for the OP that this isn’t reliant upon what we would restrict to a fluid flow effect. It would work perfectly well if you pushed a train of marbles through the tubes.

In describing the manner in which the meter works I would avoid mentioning Coriolis. The key is conservation of momentum. That is most certainly a principle, and better, a law. You can go deeper if you wish.

I agree about using the term “Coriolis effect”, in the video this term is being used as a marking gimmick … “Coriolis mass flow meter” just sounds brainier.

We need to be careful applying our Law of Conservation of Momentum. It is true that the momentum of the water coming in is exactly the same as the momentum of the water leaving (ignoring friction), however while the water is within the system it’s momentum is changing almost constantly.

Let’s consider the rotating apparatus. With no flow of water, the energy used to start the rotation is applied to the momentum of both the water and the pipes. Once we reach our desired rotational speed, everything has the momentum it needs and the pipes are square and true. However, if we move that water down-pipe, the water coming in will have less momentum than the pipe, so the pipe must give up some of it’s momentum to the water and this causes the pipe to lag behind the rest of the apparatus. Similarly at the other bend, the water has more momentum than the pipes and the water must give up it’s momentum to the pipe causing the pipe to swing ahead of the apparatus.

This set-up is impractical for the typical home water meter, so we take advantage of basically the same effect in an oscillating apparatus, the forward bend is constantly adding momentum to the ‘new’ water and the backside bend is constantly removing momentum from the water.

The key here is that energy is being added to the system, and this energy is being used to perform honest work. We know exactly how much energy is being added, we simply measure the work being performed and this will give us (eventually) the mass of what the work is being performed on, which here is the water.

The Coriolis force is a pseudo-force, thus by definition does NO work … therefore mass flow meters do not rely on the Coriolis force in any way what-so-ever.

Actually, looking at the wiki, I think this IS the Coriolis effect, and calling it so is perfectly cromulent.

From the point of view of the rotating pipe, the water moving outward appears to be pushed against the pipe, in the opposite direction to the rotation, and vice versa for the water moving inward. This is pretty much what the Coriolis force/effect is.

Yes the ‘Coriolis force’ pushing the water sideways is a pseudo-force. In the non-rotating frame of reference what’s clearly happening is that the pipe in the outbound leg is exerting a force on the fluid, which, because there’s no real force opposing it, accelerates the water. No Coriolis force at all.

These were cool sites. My mind was blown. I’m wondering how they measure the “twist” induced in the loops by the flow. The vibration is supposed to be quite rapid. Is that optical? Capacitance of wires attached (but not in diagram)?