# Tagged Questions

The quantitative study of how fluids (gases and liquids) move.

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### Can u explain below diagram is possible or not [closed]

If I takes 3 balloons with same size they r connected with same thred frist end have 2 balloons and second end have 1 balloon I put same manner as shown in diagram then frist end is gos up or not or ...
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### How to reduce surface tension of water?

I'm working on a project and I need to reduce the surface tension of water. I want you to tell me a way in order to reduce surface tension of water except changing the temperature.
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### Numerical problem on Viscosity [closed]

A horizontal tube of radius $1\ \mathrm{mm}$ and length $40 \ \mathrm{cm}$ is connected to the bottom of a cubical tank of sides $100\ \mathrm{cm}$ containing water of viscosity $0.01 \ \mathrm{poise}$...
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### How does Bernoulli's principle produce wing lift? [duplicate]

In the Ray Kurzweil's book How to create a mind is said that: The mathematics of how Bernoulli's principle produces wing lift is still not yet fully settled among scientist [...] What does ...
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When deriving the sound wave equation: $${1 \over c^2} {\partial^2 p' \over \partial t^2 }= \Delta^2 p'$$ by linearizing the Euler equation: $$\rho {d v \over dt }= - \nabla p$$ and the continuity ...
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### Bernoulli Principle and pressure function

I have read in several places now that for compressible flow the Bernoulli equation $$\frac {v^2}{2}+ P\ + \Psi = \text{constant}$$ requires: $$P=\int {dp\over \rho(p)}$$ But I don't get ...
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### When can we just look at just the partial derivative of energy?

I am reading a text about fluid mechanics and in the chapter about the (zero viscosity) Wuler equation this showed up: We consider now the kinetic energy and the internal energy of the system and ...
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### flow rate in split bottleneck

water flows from top to bottom. first there are two pipes, one with 10 LPM max flow rate and another with 20 LPM max flow rate. they both go to another pipe, which is 20 LPM max flow rate. the total ...
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### Why does Torricelli's law seems to fail when water speeds up after I put my finger in a hose?

We are taught that the speed of the fluid through a hole in a water filled tank obeys Torricelli law: $v=\sqrt{2gh}$, thus the speed is independent of the size of the hole. Why is it then that making ...
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### What causes loud sound when popping a baloon/bubble?

As I chew my gum, I wonder: when I blow and pop bubbles, what creates the snapping sound? Or similarly, what causes the loud POP when one pops a balloon? Is it the rush of air from inside the pocket ...
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### Single fluid simulation algorithm

Every fluid simulation I've seen implicitly involves a fluid that isn't mentioned, usually air. This is clear because the simulation usually has an ambient temperature, and always an ambient velocity. ...
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### Directional resistance in water

How do I calculate the change in resistance in a sealed central heating system, in respect of using a T or y section, I.e, when water flows ⬆️ through a T resistance is split equally at the ...
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### How viscosity and velocity relate in a pipe?

Assume we have a pipe that there is a fluid stream in it. By increasing the velocity of the fluid the resistance will increase either (because of the viscosity I think). My question is how are these ...
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### Air flow through a tube

During a discussion, a friend explained to me that the volume of air flowing through a tube could be increased up to the point where the air reached supersonic velocity. Presumably the pressure ...
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### How does air travel after leaving air nozzle?

I am working on a project which involves air nozzles. I am interested in estimating the time it takes for air particles after they leave the nozzle to reach a particular distance away. I have the ...
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### Why does water not fall out of a pressurized tank? [closed]

Would water fall out of a pressurized container or not? I'm guessing it would because the internal pressure would cause the water to rush out of the container. A capped container contains water under ...
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### Can a compressible fluid flowing , change its speed in the absence of a pressure gradient?

I've heard that in a high velocity nozzle, any random 'fluid particle' experiences an increase in kinetic energy at the cost of internal energy and pressure energy.And I do understand that for any ...
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### What is meant by the Laminar boundary layer equations?

I have a question and it is to briefly explain (do not derive) the laminar boundary layer equations. I need to understand what the underlying ideas and how the equations are employed. Any help would ...
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### Fluid motion videos [duplicate]

I am looking for references to papers and research problems involving fluid mechanics, and in particular animal/plant/bacteria locomotion, that could be illustrated by showing a video like these. It's ...
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### The equation of continuity in isothermal system in spherical axis(transport phenomena)

My homework is about finding the equation of continuity in isothermal systems in spherical axis, I can't imagine a workaround for that since its a little complicated for me to understand velocities ...
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### What are the factors on the volume of a drop?

Earlier today I grabbed a flask of sweetener and reading through the nutrition info I found this "Approximately 0.2cal per 0.2mL or drop". So I started thinking, what affects the volume of a drop? Is ...
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### A leaf floating on the surface of water (in $x$-$y$ plane) curl along positive $z$ axis [closed]

A leaf floating on the surface of water (in x-y plane) show that for a very small circular leaf ($\nabla \times \overrightarrow v$) is equal to twice the angular velocity of rotation of the leaf, ...
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### What is Pressure Energy?

While deriving Bernoulli's Theorem, our teacher said that the sum of KE, PE and Pressure Energy per unit volume remains constant at any two points. P + \rho g h + \frac{\rho v^2}{2} = \text{...
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### How does a building lose heat through a gap in the external wall?

Consider a building in a cold climate with a temperature difference of 20 degrees C, i.e. external temp. is 0 degrees C and internal temp is 20 degrees C. How does a building lose heat through a gap ...
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### Wind velocity required to get a flag flying/waving - is there a formula to estimate this?

For example, the giant flags here are 300' x 150 ' with 1,100 lb weight. A question was asked about how much wind would be required to "fly" such a flag given a tall enough flag pole. A Google search ...
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### What causes angular deformation in an inviscid free vortex?

We can describe a two-dimensional (i.e. planar), inviscid, irrotational, free line vortex in cylindrical coordinates with the stream function $\psi = -K\ln{r}$, velocity potential $\phi= K\theta$, ...
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### What is the difference between the Method of Characteristics being formulated in terms of theta & alpha and theta & nu?

So I'm doing an MSc thesis involving the method of characteristics in rocket nozzles. My lecture notes have the MoC formulated such that the positive characteristics are defined as: C+ = Tan ( \$\...
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### Reference values for viscosity and density in incompressible NSE

I come from a pure mathematics background, so I have very limited physics knowledge. I'm currently working out the non-dimensional form for the Navier-Stokes equations and have some questions. Where ...
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### Navier-Stokes: equation or equations [closed]

In textbooks and papers, you see both forms: the Navier-Stokes equation and the Navier-Stokes equations. Which one is correct and why?
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### Energy-Mass Equivalence applied to governing equations

To start off with this is an extremely general (vague) questions, and as such I expect vague answers. I've recently been studying the Navier-Stokes equations which govern fluid motion. These ...
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### I have problem understanding the direction of the shear stress [duplicate]

Is it in the direction of the velocity ? If it is, can anybody describe it somehow that matches my physical feeling? How the shear stress affects another layer of fluid ? I faced a question ...
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### Is it possible that my 750ml water bottle contains spent fuel from a space shuttle launch

Firstly I live in New Zealand which is very distant from USA which is where the space shuttle was originally launched from. So what is the possibility of molecules from the rocket engines spent ...