Questions tagged [bernoulli-equation]

An equation governing fluid flow for an incompressible steady fluid

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Potential Energy of A Fluid

For Bernoulli's theorem, the equation is $$P + \rho gh + \frac{\rho v^2}2 = \text{const}.$$ I know that these terms are pressure energy per volume, potential energy per volume and kinetic energy per ...
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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 ...
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Water pressure out of pipe insertions in a bigger pipe in which water is flowing

I've got a very basic knowledge of fluids and can't comprehend this situation. I've tried to look it up on my own but I guess I couldn't find the right keyword to search. I've got a pipe P in which ...
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Brains, Kinked Veins, and Pressure [closed]

My physics has degraded from mathematical to intuitive, always a problem. Asking for help with what appears to be a simple problem that starts here: fluid flowing in a tube at a given flow rate ...
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Bernoulli principle and vertical flow

I know that the Bernoulli principle applies to a horizontal flow. I would like to ask with a vertical flow (liquid or air going from top to bottom), Bernoulli principle has been applied?
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Rocket Propulsion and Bernoulli's Theorem

This is what my textbook says on rocket propulsion:$\hspace{75px}$ Questions: The beginning of the textbook excerpt says that the fuel is converted into a gas at high pressure. Does this mean that, ...
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737 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 ...
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Why shouldn't we stand near a moving train?

My physics teacher says, “ When a train moves, there is a matter wave attached to it. Waves move from positive to negative. Outside of train is positive and inside is negative. So, the train may ...
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Is liquid exchange between two compartments limited if one has 1000-fold smaller volume than the other?

I would like to 3d-print a structure made of two connected compartments and fill the whole thing with a liquid. Both compartments are approximately spherical but one is about 1mm3 and the other 1cm3. ...
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492 views

How does an aspirator pump work?

The below picture is of a aspirator pump. If we press the bulb at A the air in it with density $\sigma$ will flow out with velocity $V$. This would cause lower pressure at B and hence the liquid with ...
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326 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 ...
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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...
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Vasodilation decreases blood pressure

Okay it should make sense intuitively, but Bernoulli's principle says that a higher cross sectional flow area means less velocity which means higher pressure! I also read in a related post that ...
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Theoretical vs Experimental flow rate of fluid coming out of a water bottle with a hole in it

Say there is a water bottle that is filled with 300 mL of water and has a circular hole with a radius of 2 mm. In this bottle, the water sits 7.8cm above the top of the hole (which has been drilled 1....
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How does the depth of a water bottle affect the water pressure (fluids)

If you take a water bottle full of water, and make a hole near the bottom, water obviously spurts out a certain distance. How does the variance of the size of the hole made affect how far and how fast ...
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Bernoulli's equation: tube attached to a filled tank

I have the following problem where I need to apply Bernoulli's equation to find the velocity at the end of a tube that is attached to a hole of tank (filled with water), like it is illustrated in the ...
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Problem with Torricelli's law homework

I am trying to solve my physics homework about a Rainwater tank. The tank has a diameter of $0,50m$ and a height of $1m$. At the bottom of the tank there's a hole with an area $A=1mm^2$. The tank is ...
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Why is pressure greater in an open part of a tube than in a constricted one?

I have read that in an artery, the blood pressure is greater in an opene artery than in a blocked/constricted one. Why is this the case? Looking at the Bernoulli equation, Pressure + 1/2*density * ...
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What are the assumptions made to apply the Bernoulli's principle in real life conditions?

I have seen multiple times and places that many ideal laws are easily made applicable on real life situations. For example, Bernoulli's equation or principle is made as a good equipment in solving ...
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Which force cause to the velocity change in a fluid

I am not hoping an answer with the description of Bernoulli's equation, but rather a more detailed description. According to this picture it shows that when the area is law, the velocity increases ...
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How is work done in a nozzle zero

Fluid flow gets accelerated through a nozzle. As the flow is accelerating( and there is a change in momentum). According to Newton's second law we can say a net force is acting on the fluid through a ...
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478 views

Problem with the Bernoulli's equation for fluids

Suppose we have a $U$ shaped hollow tube consisting of three parts as : $T_{v1}$, $T_{v2}$, and $T_{h}$ , representing two vertical tubes and one horizontal tube respectively. The configuration is ...
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Bernoulli's Principle and Water Hoses

I am having trouble understanding the relationship between fluid velocity and pressure in a defined space such as a hose, pipe, etc. I understand that, by Bernoulli's Principle, the pressure of a ...
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What is the pressure term appearing in Bernoulli's Equation? [duplicate]

In Bernoulli's equation the pressure plus kinetic and potential energy is constant. But what is this pressure term, physically? Is it the pressure of the fluid on the walls of the container or is it ...
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501 views

How to calculate the flow rate?

Given a tank with a certain height of water above the discharge pipe of know length, open to the atmosphere at the other end. I know the flow rate can be calculated if the pipe was horizontal by using ...
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Confused about applications vs misconceptions about Bernoulli principle

I've been reading on wikipedia that the Bernoulli principle is often incorrectly applied to the example of blowing on pieces of paper because A third problem is that it is false to make a ...
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What is a simple, effective, and physically consistent explanation of Bernoulli's principle (in the context of airfoil lift)? [duplicate]

I am not here to continue any debate about what really allows airplanes to fly. Rather, what I am looking for is an informed, thoughtful, illuminating and self-contained explanation of Bernoulli's ...
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If fluid flows faster through a narrower pipe, why do hourglasses work?

I'm essentially describing a fallacy due to a flaw in my understanding, and I'm trying to understand what the flaw is. I know that if a pipe narrows, the fluid moving through it will move faster to ...
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Floating sketchpen?

This post is about an experiment of mine , which was for me, remarkably interesting! Why do I post it here? I'm interested in knowing the physics behind this. MATERIALS USED A light weight ...
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Wind Power in a Wind Tunnel

Two questions in one day! What? Okay, so the power equation for air flow is as follows: $$ P = 1/2 \cdot \rho \cdot A \cdot V^3 $$ In a wind tunnel due to the Bernoulli principle as the area ($A$) ...
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How do you determine the pressure of water at the surface?

Using Bernoulli's equation, how would you determine the pressure of the water at the surface in a vacuum? I have tried figuring this out and I believe it would be 0pa due to the height of water ...
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Derivation of Bernoulli's Equation

In the derivation of Bernoulli's equation through conservation of energy, as shown in http://www.4physics.com/phy_demo/bernoulli-effect-equation.html, the net work done on a section of fluid is ...
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Bernoulli's theorem

In Bernoulli's theoram as stream lines cannot intersect each other and even water is nearly incomprehensible then how is it possible to all the water which got in come out, eg 100 stream lines goes in ...
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How does the standard derivation of Bernoulli's Equation work?

How does the standard derivation of Bernoulli's Equation work? So, the derivation itself (the work energy theorem one) is pretty simple, but the work-energy theorem is supposed to be applied to ...
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Question about Airy wave theory

I have a fundamental misunderstanding about Airy wave theory. All the texts that derive the dispersion relation for gravity water waves use as a final step the unsteady Bernoulli equation: $$\frac{\...
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A paradox when I was deriving Bernoulli's equation from energy equation

I am having an exercise: Deriving the Bernoulli's equation ($\space p_1+\frac{1}{2}\rho V_1^2 = p_2+\frac{1}{2}\rho V_2^2 $ ) from the energy equation: $$\rho \frac{D(e+V^2/2)}{Dt} = \nabla(pV)$$To ...
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563 views

Determine Pressure before and after Pump [closed]

I've been trying to solve this (exam) question but keep getting wrong answers. I need to calculate P1 (pressure before pump) and P2 (pressure after pump), the pump drives a fountain. Given ...
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587 views

About Torricelli's law derivation: $p_1=p_2$?

When deriving Torricelli's law, pressure at points 'a' and 'b' are said be equal to atmospheric (Figure 1 below). Torricelli's law became a specific case of the Bernoulli's principle, whose ...
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Bernoulli's principle and deduction of the velocity field

Bernoulli's principle states that, on a streamline of a incompressible inviscid steady fluid flow, we have that $$ \frac{1}{2}v^2 + \Phi + \frac{P}{\rho} = const $$ The constant on the right hand ...
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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 ...
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Are pressure and velocity uniform for a cross-section of fluid flow?

The flow depicted in the figures is irrotational and the fluid is nonviscous, incompressible. My questions - Is pressure uniform and constant for the whole cross-section(depicted by $A_1$ and $A_2$)...
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Why can Bernoulli's equation be applied along two different streamlines for an irrotational flow?

The following is written in Physics by Halliday, Resnick and Krane (5th ed.). $$p + \frac{1}{2} \rho v^2 + \rho g y = \mathrm{constant}$$ Strictly speaking, the points to which we apply ...
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How does this cup-with-a-cylinder-inside puzzle work?

There is a desk-top puzzle making its way around my university, sold as "Newton's Gravity Defying Puzzle". It consists of a cup with a little cylinder that sits inside. Here are some pictures: The ...
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What physically happens to decrease the pressure when the velocity of a fluid increases

Neglecting any special cases and generally speaking, when the velocity of a fluid increases the pressure decreases (Bernoulli's principle). This can be observed in experiments like "air over paper" ...
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Why neglect gravity in Kutta-Joukowski theorem?

In an example I was asked to calculate the lift force using Bernoulli's equation $$u^2/2 \ + p/\rho +gz \ = \ constant$$ and show that its consistent with Kutta-Joukowski theorem, but seems like ...
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Is water lost in a pipe?

If I have a very long (say, 1km) pipe in my garden (under the sun) with a small slope and put water at one end, will I receive exactly the same amount of water at the other end, with the same pressure ...
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Why is a piece of paper lifted upward even when blown below?

According to Wikipedia, A correct explanation of why the paper rises would observe that the plume follows the curve of the paper and that a curved streamline will develop a pressure gradient ...
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How to picturise the flow of the ideal fluid?

This bent, flat tube is located on a horizontal plane and ideal fluid is flowing through it, as shown by the arrows. According to me, pressure at 2 would be higher than pressure at 1. I think so ...
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Water in the bunker problem

We have a bunker(Like a Cylinder), full of water with height $H$ initially, there is a whole at the bottom of the bunker. The pressure of the air outside is $P_0$. The surface of the bunker is $A$ and ...
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How do I apply Bernoulli's equation in a rotating frame of reference?

I intend to apply Bernoulli's equation in an annular swirl flow where v_z is constant, omega_z is dependent on radial location. I need to apply the Bernoulli's equation in a reference frame rotating ...