# Questions tagged [bernoulli-equation]

An equation governing fluid flow for an incompressible steady fluid

381 questions
Filter by
Sorted by
Tagged with
39 views

### Pressure Variations in an Atomizer

This question has been asked two times Similar question 1 Similar question 2 Now my question will be different from all those questions, since I will be asking where exactly I am having trouble ...
1k views

### How does this spray gun work?

This is the critter spray gun. The liquid in the jar is at atmospheric pressure (there's a vent hole connecting it to the atmosphere). A fast jet of air flowing right over the end of the pickup tube ...
97 views

### Why do we need to do work to maintain motion of a fluid?

On page 355 of principles of physics by Resnick walker and Halliday, the author writes: Work must also be done on the system (at the input end) to push the entering fluid into the tube and by the ...
103 views

### Concept regarding Ventury Tube-Bernoulli application

I was recently studying applications of Bernoulli Equation and came across the Ventury tube. This is diagram I have used to analyse the venturimeter. I understand how we obtain the first equation ...
40 views

### Zero velocity at a point in a streamline

Given a streamline, is it possible that the velocity at some point on it is non-zero but then at some other point(for example, stagnation point) it is zero? I mean does that make sense? My existing ...
2k views

### Maximum liquid velocity in a siphon

According to wikipedia: Siphon, the velocity of liquid in a siphon is equal to $\sqrt{2gh}$, where h is the difference in level between the water surface and the opening of the siphon. But it also ...
16 views

### Pressure at the opening of tube in Siphon

Consider a siphon tube... Now consider the opening of the tube at the lower end. Isn't the pressure at the mouth of the tube, at this lower end, something intermediate between $P_a$ and $P_a + \rho gh$...
199 views

### How to find velocity of water flow and $Q$ if I know static pressure at the end of the pipe of known diameter?

I have a pipe. At its end I have mounted pressure meter. Of course there is no circulation. Water pressure meter is a kind of stopper for water. I know diameter of the pipe, and I know its pressure in ...
53 views

### 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 ...
44 views

### Explaining Bernoulli's Principle

I'm trying to explain Bernoulli's principle (in the context of flight) to an audience that doesn't have a physics background. So I'd like to avoid mentioning technical concepts as much as possible. ...
2k views

### Why doesn't Bernoulli's Principle apply to Current and Resistors in a circuit?

Bernoulli's principle makes sense when you apply it to fluids. If you decrease the diameter of a pipe then the velocity of the fluid increases because it needs to keep the same rate of fluid moving ...
319 views

### What is the relationship between flow work and velocity of gas?

As we know that for open systems, we have energy conservation equation as $$h+\frac{v^2}{2}+zg=const.$$ $$h=u+pV$$ $$u+pV+\frac{v^2}{2}+zg=const.$$ Here $pV$ is flow energy. We know that all these ...
147 views

### Flow through a hole in a sphere

I have a sphere of diameter $D$ (radius $R$) with a small hole of diameter $d$ (radius $a$) in it, with air flowing through the axis of the hole: I am trying to estimate the drag force due to ...
191 views

Suppose I have a fan blowing air. By Bernoulli's equation, the air pressure in the stream is lower than the air in the surrounding. Here is my confusion: the moment I turn on the fan, the fan starts ...
149 views

### Bernouli equation on streamline

I made my first point at the free surface of the water and my datum to be the very bottom. Part (b) of the question asked to find the velocity of the water in the pipe. I set my second point to be at ...
136 views

### 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 ...
333 views

### What happens if a helicopter's propeller spins in reverse?

I know airplanes and helicopters fly thanks to the same principle, the Bernoulli Principle. The wings and blades are designed so that the air travels faster across the up side than it does on the ...
24 views

### Is there a drag in a moving fluid due to pressure (reaction) from the walls of the tube?

Consider a tube of linearly varying cross section... Now consider a section of the tube...There are pressure on the ends of this section due to the fluid... Now consider the walls, there is a ...
386 views

### Doubt in derivation of Velocity of efflux (Torricelli's theorem)

To find the velocity of efflux of fluid from a hole in a simple cylindrical container we use the Bernoulli's equation. $$P + ρv^2/2 + ρgh= constant$$ For our specific case we take the pressure at ...
36 views

### Intuitive explanation of the causality behind a pressure gradient forming

The Bernoulli equation as a statement on the conservation of energy as I understand it is the observation in an idealized flow that the bulk fluid velocity relates to the kinetic energy of the fluid ...
128 views

### How to determine effect of obstruction on pressure?

I am struggling to figure out what theory explains a situation I observed. A steam boiler had a pressure control which would turn off the boiler if it sensed 2 psi. The boiler would frequently switch ...
149 views

### Do viscous and inviscid flow have opposite effects on pressure?

Consider flow through the converging and diverging portions of a tube with varying radius: In inviscid flow, Bernoulli's equation states that velocity at the throat will be the highest, so this area ...
49 views

558 views

### If the difference in pressure is zero between two points of a horizontal constant radius pipe, why isnt flow rate zero?

In a straight pipe of uniform cross-sectional area filled with a nonviscous, incompressible fluid, the pressure at one end is equal to the pressure at the other end. Which of the following statements ...
402 views

### 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?
18 views

### 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 ...
51 views

### 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 ...
30 views

### 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 ...
993 views

### How to apply Bernoulli's equation on an experiment of rising water with a straw?

Consider the following experiment: Rising a water in a straw. For the sake of simplicity, let me assume that there is no air in the straw by redefining the height h...
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 ...
523 views

What is pump head? and how is it different from the difference in elevation between the suction and delivery reservoir? Also why must the kinetic energy of the fluid leaving the pump must be least? I ...
35 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?
70 views

### 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 ...
38 views

### 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 ...
303 views

### Mathematical description of Bernoulli equation and transition from laminar to turbulent flow

I am very interested in the mathematical description of the next topics: 1. Bernoulli equation 2. Transition from laminar to turbulent flow Could you help me ...
20 views

### 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 ...
25 views

### 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 ...
348 views

### Why don't we consider the pressure due to height of liquid column above the orifice while calculating the speed of efflux using Bernoulli equation?

While describing speed of efflux, using Bernoulli equation, we use value of $P$ at both openings as atmospheric pressure. Why don't we use $P_\text{atmosphere}+\rho gh$ for $P$ at bottom opening?
293 views

### 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 ...
901 views

### Static Pressure in a Venturi vs a Free stream

We seem to have two conflicting measures of pressure in a Venturi siphon open to the atmosphere,$\hspace{100px}$. Bernoulli's principle says that, by energy conservation for a steady flow $Q$, the ...
3k views

### Total and static pressure: which one is measured?

Which pressure is measure using measuring device in a pipe flow. My first intuition that it is the static pressure. This is confirmed by this Wikipedia article (link) The concepts of total ...
164 views

### Which equations recommend to model a flux through a Bernoulli tube?

Which equations recommend to model a flux through a Bernoulli tube? The velocity of the flow varies very little along the tube, in addition the tube has different transverse areas. I am doing a ...
3k views

### Inverted U manometer

I have some doubts on inverted U manometer. In the picture there is one U inverted manometer, the space above the liquid in the manometer is filled with air which can be admitted or expelled through ...
196 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 ...
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_{...