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Questions tagged [bernoulli-equation]

An equation governing fluid flow for an incompressible steady fluid

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Where does the acceleration come from in a hose Nozzle?

If we start with a short straight hose out of the side at the bottom of a tank of height H the simplest derivation of Bernoullis along an inviscid streamline 1/2v1^2+pgh1+p1=1/2v2^2+pgh2+p2 shows ...
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Material Derivative in Fluid Dynamics and Bernoulli Flow

If a fluid flow, such as water, is incompressible then the convective derivative term in the material derivative is equal to zero. How then, in a Bernoulli flow where there is an increase in velocity ...
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Bernoulli Experiment, unanswered questions

In the bernoulli experiment, the pressure on one side is greater than the other, thus the fluid flows faster through the thinner nozzle.In the image, is the pressure created shown correctly? Since ...
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Question derived from Bernoulli's book “ Hydrodynamica” and his contribution to atomic Theory

Here is the extract from the book Now the weight $π$ is sought which can compress the air $ECDF$ into the space $eCDJ$, the velocities of the particles in either air (the natural and the ...
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Bernoulli and the Venturi effect vs pressure

I am having a hard time understanding how pressure changes as related to flow, and also as it relates to the ideal gas law, assuming ideal conditions. According to Bernoulli's equation, as pressure ...
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Does bernoulli's principle explain the suction by an emerging air stream?

Consider flow exiting a nozzle into atmosphere, its static pressure will decrease through the nozzle as the molecules vectors align with the direction of the exit. However, as soon as it exits the ...
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1answer
27 views

Why does a ping pong ball on a string move toward a running stream of water?

We keep a ping pong ball on a string near a faucet but not directly under it. When we run the water, the ball moves to the stream and sticks there. I'm only interested in the moving part not the ...
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How does a sonic jet attenuate a sound wave?

Let's assume air flows through a pipe and exits into free atmosphere. The atmospheric pressure is below the critical pressure of the flow, hence the gas is accelerated and a sonic jet forms at the ...
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Couette Flow encountering an airfoil obstruction

Im interested in what would happen to an airfoil place within a Couette type fluid flow bounded between a fixed and moving boundary plate If we say the plate is infinite to establish a steady state ...
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4answers
81 views

Calculating value of $g$ from Torricelli's law

For my Physics project, I decided to do an experiment with fluids. I'm using the Torricelli's law to verify that the value of acceleration due to gravity on earth is $9.81m/s^2$. I am using the ...
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1answer
18 views

Magnus effect without windspeed

Canagnus effect take place if windspeed is 0 ? Lets assume that our frame of reference a place an earth (e.g. soccer pitch) .We measure the windspeed and we find it zero.But if we make a knuckleshoot ...
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Bernoulli principle and relativity [duplicate]

Bernoulli principle has many applications like airplanes take off etc. But when we apply Bernoulli's principle we dont refer the reference frame in which we measure the velocity of air for example. ...
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Applying Bernoulli's equation in fully developed viscous pipe flow

Can we apply the inviscid Bernoulli equation $$ \frac{P}{\rho} + \frac{1}{2}V^2 + gz = constant$$ along the center line of a fully developed pipe flow? I think we can since the shear stress along ...
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Do the height of the water columns decrease when we push pistons with constant speeds in this venturi pipe?

Let say when the pistons are kept stationary the height of the water columns are h. And we start exerting extra force on the left piston in figure, and the pistons are moving with constant speeds. ...
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51 views

Proof that pressure rises in a fixed control volume

I am looking for a proof using Bernoulli's equation that that for $Q=(Area)(Velocity)$, $Q_{in}>Q_{out} \Rightarrow P_{inside}>P_{outside}$. I read that for a computer, if the case fans blow a ...
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1answer
68 views

Principle of Lifting of an Aircraft [duplicate]

While using the Bernoulli's equation to deduce the upthrust on an aircraft , a statement is always made that The air particles going above th wing have to cover a greater distance in same time than ...
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1answer
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Increase Air Speed at outlet

I have a set up that inflates a rubber jacket in order release the metallic rings from underneath it. I am currently having issues with not having enough pressure (force) at the outlet to inflate the ...
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How to use General Energy Equation in parallel pipes?

My question comes from exercises with parallel pipes such as this. I know that to analyse internal flow, we use general energy equation which origins from the 1st law so each time we apply it we are ...
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Limitations of converting pressure into kinetic energy

Bernoulli's principle states that an increase in the kinetic energy of a fluid occurs simultaneously with a decrease in pressure for isentropic processes. What then limits us from converting all of ...
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Pressure in speed of efflux

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?
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What does the term $P$ represent in Bernoulli’s equation?

$$P+\rho gh+\frac{\rho v^2}{2} = C$$ Does the $P$ here stand for the hydrostatic pressure exerted by the fluid on its surroundings or the pressure that’s exerted on a given portion of the fluid? I ...
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Bernoulli's principle for a liquid with non uniform density

Consider a cylindrical container (section $S$, height $H$) which contains a liquid with non uniform density. Let $z$ be the axis along the height of the container ($z = 0$ indicates the top of ...
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Pressure distribution around an aerofoil

Some notes that I'm reading right now show a picture of the distribution of pressure around an aerofoil with zero angle of attack. The notes say that the pressure is identical at the top/bottom ...
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1answer
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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 ...
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Deriving relationship about water not falling down from a hole under a fast flowing stream [closed]

A gutter is tilted from an angle of $\theta$ with respect to earth. There is a hole on the gutter from a distance of $l$ (m) from the top of a gutter. What is the speed of the water that should flow ...
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Relationship between blood pressure and cross sectional area of blood vessel

What is the reason why blood pressure and a larger cross sectional area of blood vessel cause a lower blood pressure and vice versa? This question is related to another question I found here. The ...
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Why water doesn't drop down from a hole when a stream of water travels fast over it?

why water doesn't fall down from hole on the roof when its raining heavily (water moves fast on the roof) ? Can I know the theory behind this and the factors affecting?
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Modeling water flow between two tanks

To familiarize myself with concepts from my system modeling class, I have posed myself the following problem, which I have been struggling with for a good while now. I am an absolute physics beginner, ...
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Effect of pressure when drying wet clothes in a windy environment

When we hang wet clothes outside, they dry faster if it is windy. The wind causes forced convection and removes the air saturated with vapor, and the rate of evaporation does not decrease much in ...
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When exactly can the concept of stagnation pressure be applied?

Although I've attached a homework problem here, I'm only using it for reference for a conceptual question on stagnation pressure. From my understanding, in the photo attached above, the pressure at ...
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1answer
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Why that Bernoulli function contains many streamlines and vortex lines but not only singular streamlines?

I know that for a stream line inside the gradient part equal to a constant. But when we consider the fluid is rotational which the velocity cross product vorticity not equal to zero. So how can we ...
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Water Height of a centered-hole tank [closed]

Here's the problem. A large tank is filled with water for a height $H$. In the center of the tank a circular hole with a radius $R_1 = 10$ cm is made from which the water flows vertically. We can ...
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1answer
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What is the physical meaning of static and velocity pressure?

According to Bernouli's equation, the static pressure inside a pipe with streamline and steady flow decreases with fluid's velocity. One explanation to rationalise this phenomenon is because velocity ...
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Computing the velocity of fluid along the length of a cylinder

I am modelling the flow of fluid through a cylinder of length L.The cylinder is divided into three segments(each segment of length L/3), there are four nodes(i=0,1,2,3). I'm trying to compute the ...
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1answer
39 views

Carburetor, throttle, airflow

It is said that the less we open the throttle the speed in a Venturi tube inside the carburetor is slower, thus less reduction in pressure and less fuel is being sucked from float chamber, however, ...
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Venturi effect on molecular level

Is there a good explanation why the pressure becomes lower on the narrow part of the venturi pipe? I'm not interested in the newton explanation or pressure differences explanation. I want to ...
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2answers
80 views

Bernoulli's Effect on Blood Pressure [closed]

What is the impact of height, let's say being on top of a 4,000 m high mountain, on blood pressure / flow velocity given Bernoulli's Equation?
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Bernoulli principle

I've been trying to deduce the Bernoulli's theorem but i have a few problems Why is it restricted to a streamline? Thank you very much
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256 views

Bernoulli's equation and negative pressure

Here is Bernoulli's equation: $$P_{{1}}+1/2\,{\rho v_{{1}}}^{2}+\rho {\it gy}_{{1}}=P_{2}+1/2\,{\rho v _{{2}}}^{2}+\rho {\it gy}_{{2}} $$ A friend of mine was looking at some lecture notes today and ...
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Does venturi effect violate pascal's law?

If we use Bernouill's law to compare pressure between point 1 and point 2, we find that P(2)gdH=0, we conclute P(2)=P(1). I must have made a mistake but where is?
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Is it possible to create circulation of water in bypass pipe without water pump?

There is a pipe of 32mm in diameter. Water flows from left to right. There are two branches in that pipe. To one of them connected input of water heat exchanger, to another - output of water heat ...
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1answer
52 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 ...
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2answers
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What do I need for a good flow of water from a faucet: velocity of water or pressure?

I can't understand one thing. A good flow of water from bath faucet requires a good velocity of water or a good pressure? For example, I have a crane that has a pipe diameter of 1 inch. The better the ...
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2answers
136 views

Is equation of continuity valid even against gravity?

Consider a tube having variable cross section and is placed vertically. The upper part it has a cross section of $4\ \mathrm{mm^2}$ and the lower part has a cross section of $2\ \mathrm{mm^2}$. If ...
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1answer
45 views

For a fluid travelling in a tube, if the pressure is decreased at a constant temperature, how does it affect the velocity and fluid density?

I am interested in understanding the relationship between pressure and velocity, as well as pressure and fluid density. I know that the principle of Bernoulli states that there exists a relationship ...
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2answers
78 views

Work-energy theorem and Conservation of energy formula

We have $$W_{net}=\Delta K \quad(work-energy\; theorem)\tag{1}$$ And also $$W_{net}=\Delta K +\Delta U \quad(Conservation\;of \;energy \;formula)\tag{2}$$ How's that happening? In proof for bernoulli'...
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Eulerian approach to control volume and energy conservation equations

After refreshing/researching the Eulerian approach to conservation equations for mass, energy, momentum I am struggling with understanding the partial derivative term that I believe represents ...
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1answer
304 views

Energy loss in Fluid flow

In a constant diameter, ground level pipe of substantial length to reflect a pressure drop of dP, how would the loss of energy be accounted for? The assumption would be that kinetic and potential ...
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203 views

Torricelli's Law and Variable Density

I wish to explore a slight modification of a well known result found in several physics texts - Torricelli's Law of Efflux. The most common problem on the above result has the following setup: The ...
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1answer
149 views

Deriving the expression for the height of liquid in a cylinder spinning on a turntable using Bernoulli's principle

When a liquid in a cylinder is spun on a turntable, it will experience a vortex or whirlpool effect, as shown below: I have seen and understood a proof for the value of $h$ by taking the motion of a ...