Questions tagged [bernoulli-equation]

An equation governing fluid flow for an incompressible steady fluid

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Semantic question about Pressure in fluid

I have a semantic question about Bernoulli's equation, I learned that Bernoulli's equation is: $$\frac{v^2}{2} + \frac{P}{\rho} +gy=const.$$ My question is why is it that at point $C$ the pressure is $...
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Why does the pressure inside a pipe momentarily increases when the tap is closed?

I fill coolers in my house with a pipe connected to a tap, as soon as it is full i place a thumb on the open section of the pipe effectively shutting off the outflow of water. Keeping my thumb in ...
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What force accelerates a liquid moving in a narrowing pipe?

Say there is a liquid which behaves like an incompressible fluid and is flowing steadily through a pipe which is moving from a cross section of area $A_1$ to the cross section of area $A_2$, where $...
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Explain hydrodynamic Levitation

I had researched it and I saw everyone has there different answer. Someone says its Magnus effect, someone says it is Coanda effect and someone says its Bernoulli's principle. Can it be specific? What ...
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How does high velocity cause low pressure? [duplicate]

Bernoulli's principle states that air molecules moving with high velocity create an area of low pressure which in turn causes an object to fly, but how does high velocity cause low pressure?
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About deriving bernoulli equation from particle model and its pressure difference

Here i added a page from my fluid dynamics book where it shows particle model for deriving the equation. My question is why pressure is more at stream side aka 'positive "s" direction'.I would ...
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1answer
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Does Bernoulli's equation describe why my curtains stick to the mesh?

I was sitting right in front of a big window (with a mesh) with curtains open, suddenly wind swooshes in, curtains sway forth and back. While they sway backward, they stick to the window(mesh) as if ...
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Does the number of holes in the bottom of a bucket determine the height at which the pull of gravity overcomes the surface tension?

Ok, my colleague and I are having a debate that we need help with. Neither one of us works in this space (chemist and materials scientist) and we understand this should be pretty straight forward ...
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27 views

Does high pressure force an object to a lower pressure area?

Suppose a ball is spinning through mid air. We know through the Magnus effect the way the ball will go. On the side where the air flow is slowed down due to the spin of the ball, the pressure ...
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1answer
34 views

Why does the air flowing above the aerofoil moves faster than the air flowing below the aerofoil? [duplicate]

https://www.youtube.com/watch?v=UqBmdZ-BNig why can't it be the other way around that the air flowing below the chamber moves faster than the air moving above the upper chamber?
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A contradiction from two reliable sources on the principle of how siphons work

At 39:08 of Lecture 28 of 8.01x by Walter Lewin, a water siphon would not work if the distance is over 10 meters due to the barometric pressure. However, this claim is seemingly refuted by Periodic ...
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How does pressure become velocity in a jet engine axial turbine?

All right. Here's what I understand about axial turbines: It is an axial compressor in reverse. An axial compressor forces air to flow in an increasingly tight space, where there is not enough ...
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Does the shape of the pipe (the length not the cross section area) affect resistive force?

Does the shape of the pipe (the length not the cross section area) affect resistive force acting on water? Does keeping the pipe straight or keeping it in curves folded over each other effect the ...
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When solving using Bernoulli's principle, is the pressure potential energy per volume of atmospheric pressure water 0 Pa or 100,000 Pa?

I was just given a question using Bernoulli's principle that gives you the pressure of water (e.g. $1,000,000 \mathrm{Pa}$) in a hose, and asks for the speed of the water after the water has left the ...
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Could the Bernoulli equation be explained by kinetic theory?

I have watched on the Youtube channel of Eugene Khutoryansky an explanation of the Bernoulli equation on the molecular level. It states that" An atom is more likely to enter the narrow section of a ...
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1answer
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Calculating the flow rate in a non-ideal siphon?

When calculating flow rate in a siphon, the simplifying assumption is usually made that the velocity head at the input is effectively zero. This requires that the cross-sectional area at the input be ...
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Faucet Atomizers and Aerators - Volume Flow Rate

It is said that atomization nozzles and aerators in the faucet save water. They reduce the volume flow rate of the nozzle. If this is true then isn't the equation of continuity violated? For example,...
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1answer
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Bernoulli equation constant for water waves

A fluid fills $\{(x,y,z) \in\mathbb{R}^3:y \leq0\}$. The flow $\textbf{u}=(u,v,w)$ is given by $u=k\sin(\omega t)\cos(kx)e^{-|k|y}$, $v=-|k|\sin(\omega t)\sin(kx)e^{-|k|y}$, $w=0$, for $y\leq0$. We ...
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Intuition behind Bernoulli's equation [duplicate]

If water is flowing from a larger subsection $A_1$ of a pipe into a smaller subsection $A_2$ (say, the radius halves), then Bernoulli's principle says that the pressure $P_{A_1} > P_{A_2}$, and $v_{...
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Applicability of the continuity equation

In systems such as the following; Applying Bernoulli's equation to the mouth of the tube and to the point just below the rightmost column, you get an excess pressure head on the energy sum of the ...
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28 views

About pressure work and dynamic pressure of liquids

I'm new here there are a few questions which bothering me for a while. I know that pressure times volume equals to energy. Dimensional analysis shows that. But how is that happening in reality? For ...
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Why doesn't Bernoulli's equation contain the kinetic energy correction factor?

I'm confused about the kinetic energy correction factor $\alpha$ in the Bernoulli (energy conservation) equation. The uncorrected equation is derived for an ideal fluid, and then reads $$ \frac{1}{2} ...
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Using Venturi effect for air ventilation, or, can fluid be passively driven in a loop?

My problem is practical - I have a boat that has a cabinet in it which has a persistent epoxy smell from recent work, causing all clothing stored in the cabinet to also smell of epoxy. So it needs to ...
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Bernoulli equation under free fall in inertial frame

If a cup of water with a hole on the side of the cup, then there would be water streams out through the hole. And it could be calculated by using Bernoulli's law. However, if the cup with water and ...
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Mass flow and airfoils

My understanding of airfoils is that the fluid flowing over the top of an airfoil moves faster than the fluid on the bottom, causing a net pressure that lifts the aircraft, where the air pressure on ...
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1answer
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How can I calculate flow rate and velocity of fluid at the exit of a garden storage tank?

$$P_1+\frac12\rho V_1^2+\rho gh_1=P_2+\frac12\rho V_2^2+\rho gh_2$$ $$V=Qt, \; Q=A\bar v$$ I have a tank of water in the garden and I am assuming it is full when I start watering. I'm using a couple ...
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Could there theoretically exist a material so light, that it can levitate in the air just due to the in height decreasing air pressure? [closed]

Airplanes can fly because the pressure on the top of the wing is lower than on the bottom. But the difference in pressure must be huge in order to lift an enire airplane. Also, the difference in air ...
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Velocity and pressure in vortex

I would like to ask why is the velocity lower when further away from the vortex centre and also why does the pressure increase further away from the vortex centre. When I try to do some readings, the ...
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1answer
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Air pressure dependence on temperature

I have around 200 barometers (altitude up to 200 m above sea-level) of which some in direct sunlight that can become relatively hot. I am investigating whether there is any relation between measured ...
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1answer
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Why can a helicopter fly upside down?

I saw images and video clips of helicopter flying upside down, so it can't be bernoulli principle or angle of attack of the rotary blades. So how can the upside down helicopter provide lift in this ...
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Bernoulli's principle doubt [duplicate]

Consider two points A and B on a pipe at the same height. Fluid is in a steady flow inside. External pressure is provided at point A and the fluid travels to point B. The region at point A has a ...
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131 views

Flow velocity in parallel pipes confusion

In closed pipes configured such that they are parallel in fashion, we know that the total volumetric flow rate $Q$ is equal to the sum of all $Q$s in the parallel pipes. But I have one doubt (as I'm ...
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Application of Bernoulli equation in reciprocating compressors during non-compressible flow processes

One of the assumptions through which Bernoulli equation was derived was the flow being in-compressible. I was wondering whether the Bernoulli equation can be applied during the discharge stroke of the ...
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Conservation of momentum and energy in fluid dynamics

I'm a beginner in fluid dynamics and trying to understand a few basics. 1) How do you calculate momentum in a flowing liquid? For the equation of continuity, $\Delta m$ is the same for different ...
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Why the work done by pressure is equal to $p_1A_1v_1\cdot \Delta t - p_2A_2v_2\cdot \Delta t$ in the derivation of Bernoulli's equation?

In deriving Bernoulli's equation, it is assumed that the work done by pressure on a chunk of fluid entering the pipe at point $1$ and leaving at point $2$ during a time $\Delta t$ is $$W_{p}=...
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Does Torricelli's law assume constant height?

I am planning on doing an experiment where I derive the optimal height for a hole in a container filled with water so that the stream travels the furthest. In order to determine this, I am planning on ...
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Why is the pressure force of a water jet zero?

I am tasked with calculating the force on the wall exerted by the fluid. The resultant force is equal to the rate of change of momentum and the force has a body force(gravity is assumed to be ...
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1answer
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2-D water jet on oblique plane

We have a 2-D water jet on oblique plane. We are ignoring gravity and want to calculate the force on the plane. The explanation I have been given goes as follows. We assume inviscid flow. Image is ...
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1answer
168 views

Difference between Pressure and Pressure Energy in fluids

For a fluid with viscosity to flow through a pipe that has the same cross-sectional area at both ends, at a constant velocity, there has to be a pressure difference according to Poiseuille's Law. Why ...
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Is there a height limit to the 'inflatable dancer'?

From the Bernoulli equation $$\frac{p}{\rho} + \frac{v^2}{2} + gh = \mathrm{const.}$$ along streamlines, it seems that there should be an ultimate limit to the height of an 'inflatable dancer' when ...
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How does one calculate the expected leak rate through a hole, and the pressure drop due to that leak?

Let's say we have a pressurized horizontal tube that has a hole along the way. What would be the flow rate through that hole, and what would the pressure be downstream of the hole? Or if you prefer ...
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Flow through a pipe using Bernoulli equation - Real industrial application using pressure monitors

This is not a homework question or off topic so please do not delete as previously done. I'm working in industry and need assistance on the real application. I aim to calculate the flow through a ...
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Water head and water velocity

Using Bernoulli's equation, it can be shown that the water velocity depends on the height of a tank relative to the end of a hose. In reality, I find a smaller hose produces a greater velocity on exit ...
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Some confusions about Torricelli's law

So actually I have some confusions about Torricelli's law. Based on the picture: Why is water flowing out only affected by air pressure from outside? Why not by $$P+\rho gh$$ from the water inside ...
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Extractor fans and the Bernoulli principle

Is a fan placed directly in front of a vent more efficient than if it were moved away from the vent to employ the Bernoulli principle? This is hypothetical, but using real-world examples to explain ...
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169 views

Applying Bernoulli's Principle after pipe branching (flow separates)

When I have a pipe (1) that branched into 2 pipes (2 and 3). I noticed that Bernoulli's equation can be applied between point 1 and 2 or 1 and 3. So my question is how is this valid? Isn't Bernoulli ...
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120 views

Limitation of continuity equation

Why continuity equation is not used in deriving/ finding the velocity for pitot tube where as both Continuity and Bernoulli's equation is used for deriving/ finding the velocity at throat in ...
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Toricelli and Bernoulli law - pressure definitions

Torricelli's law can be derived from the Bernoulli equation $P_1 + \rho g h_1 + \frac{1}{2}\rho v_1 = P_2 + \rho g h_2 + \frac{1}{2}\rho v_2^2$ However I don't know how to pressures $P_1$ and $P_2$ ...
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Water Bottle Rocket Thrust - two calculation methods not matching

I have been launching water bottle rockets with my kids and we are in the process of creating a simulation of the launch using numerical methods. I am a mechanical engineer, but fluid dynamics is not ...
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3answers
627 views

Bernoulli's law for turbulent flow

Is Bernoulli's law valid for turbulent flow for a non-viscous, non-compressible, non-rotating fluid with isoentropic flow? An ideal fluid has coeffieicent of viscosity=0,which implies that it's ...

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