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

learn more… | top users | synonyms (1)

1
vote
0answers
49 views

Explanation of the liquid rope coil effect

I was recently introduced to the liquid rope coil effect by this video: https://www.youtube.com/watch?v=zz5lGkDdk78 I noticed while the video mentioned the equations governing the motion, it didn't ...
0
votes
1answer
62 views

Pressure exerted by a liquid on walls of a container (quantitative)

I want to calculate the total pressure exerted by a liquid of density ρ on the walls of a container, say a cylinder, for convenience. $$P = hρg$$ Therefore integrating from $0$ to $h\; ,$ we get : ...
0
votes
1answer
54 views

Application of Bernouli's Theorem

We have to calculate the velocity of efflux in this problem. My issue is, when I apply Bernoulli about the open end of the fluid and a point just outside the orifice, I seem to get a different ...
0
votes
0answers
48 views

Stokes' law and settling particle speed

What are the forces that are exerted when a particle is dragged by air flow in a tube and settles within some distance? Does Stokes' law calculate the net force, taking into consideration of all these ...
0
votes
0answers
27 views

Lift provided to an aeroplane [duplicate]

We say that aeroplanes find lift due to an effect explained by Bernoulli's theorem. But isn't newton's third law of motion applicable along with Bernoulli's theorem? otherwise, an aeroplane wouldn't ...
-2
votes
1answer
27 views

How to calculate the time it takes water to travel 100' [closed]

100 foot of pipe(lets assume it is straight) Diameter of pipe 2" Flow rate at point of entry into pipe and exit 50gpm Temperature of water 100F 50 psi Or stated another way if I was able to ...
0
votes
0answers
30 views

Is a creeping flow with $u_r \sim \ln r$ physically possible?

I was wondering if it is possible to have a 2D cylindrical flow where the radial velocity scales with $ln (r)$. I understand that a flow with $u_r \sim 1/r$ corresponds to a line source or sink. Also ...
6
votes
1answer
917 views

Why doesnt flow of liquid from a orifice depend on atmospheric pressure?

While calculating the velocity of efflux, ie, the velocity of a liquid when it flows from a orifice which is made in a beaker filled with liquid. Since at the orifice, atmospheric pressure acts along ...
2
votes
2answers
91 views

How does a rising bubble take a dome-like shape?

Since I have swam on the swim team for most of my life, I am very familiar with bubbles. I know a raindrop falling through the sky gets its shape because it is the most aerodynamic shape, but how come ...
1
vote
3answers
119 views

General Definition of Steady State

According to many sources (including Wikipedia, Stephani&Kluge, D.J. Acheson) a steady state ist: In systems theory, a system in a steady state has numerous properties that are unchanging in ...
0
votes
1answer
71 views

Pressure and state variable: Difference between compressible and incompressible

My question: If I am simulating compressible fluids, then pressure is a "state-variable" - if incompressible, then not. Could anyone explain the difference :)? Thank you very much.
0
votes
0answers
36 views

kinetic energy of flowing fluid

When a quantity of fluid (let's say equal to volumetric flow rate Litre/s) collides during a second with an object, do all the molecules of this quantity collides with it? I am asking this question ...
2
votes
3answers
108 views

Why sphere minimizes surface area for a given volume?

I was studying surface tension recently. Rain drops or bubbles of any kind which form are always of a spherical shape. This is because the liquid tries to minimize the surface area as the molecules ...
0
votes
1answer
39 views

Need to know height of wave generated by spherical object falling into water [duplicate]

Working with an architect at present.I need to know the height of wave/ripple that would be created by a spherical object weighing approximately 10 tonnes and measuring 42 metres in diameter falling ...
29
votes
3answers
938 views

Why do particles in the molten wax near a burning candle wick get pushed away?

Have a look at this clip I made of my candle burning: I can accept that the molten wax gets sucked into the wick (though not quite sure why: capilary action?). But why does it also seem to get ...
2
votes
1answer
40 views

Friction in a fluid

when an object is moving in a fluid(air for example), the air will resist the object's movement: molecules of the air will collide with the surface of the object (no slip condition) and then we will ...
0
votes
0answers
21 views

Modeling Fluid Flow

I could really use some assistance. How would I go about trying to use Maple in order to model flow of a fluid through objects? For a rough example, such as entering an enterance of a maze and exiting ...
1
vote
2answers
44 views

Volume integral of pressure interpretation

If you have a fluid with with pressure field $p$ what is the physical significance of the the volume integral of the pressure $\int_V p dV$?
0
votes
1answer
35 views

Kinetic energy of fluid + collision

When a fluid is flowing, it has of course a kinetic energy and thus we can define kinetic power equal to ρAv v is the velocity and A is the surface of a solid for example. I have a question (maybe it ...
1
vote
0answers
16 views

Water container insulation? [closed]

If I had a 2 gallon aluminum rectangular box (quarter inch wall) full of water and had it enclosed in a thin walled aluminum shell with a quarter inch spacing which would give the best insulation ...
2
votes
1answer
38 views

Is there a conclusive correlation between viscosity and surface tension?

I'm working on a project and I need to know if the viscosity effects on the surface tension or not?
-1
votes
1answer
52 views

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 ...
1
vote
0answers
20 views

How to measure the surface tension of a liquid in contact with air? [closed]

I've used some ways to reduce the surface tension of water in contact with air ( like adding oil or electrifying the water or .... ) but now I've a question. How can measure the surface tension of ...
0
votes
1answer
314 views

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.
2
votes
0answers
45 views

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 \ ...
1
vote
0answers
33 views

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 ...
3
votes
2answers
168 views

assumptions about sound waves

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 ...
1
vote
1answer
64 views

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 ...
0
votes
0answers
31 views

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 ...
0
votes
1answer
40 views

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 ...
1
vote
0answers
53 views

What pressure will stored water at height provide from a pipe? [closed]

A big open tank is filled with water ($10000$ litres) and kept at a height $15$ metres from ground. At its bottom, a pipe of $1.5$ inch diameter and $10$ meter length is connected. The water is ...
1
vote
3answers
85 views

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 ...
3
votes
1answer
59 views

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 ...
1
vote
0answers
26 views

Turning Heat into Work [closed]

Q) I was told to create a machine which could turn heat into work. The lower its cost, the better it would be(Max around 10 bucks). The higher its efficiency, th.e better it would also be.My attemp is ...
1
vote
1answer
40 views

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. ...
0
votes
0answers
16 views

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 ...
2
votes
1answer
72 views

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 ...
1
vote
0answers
69 views

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 ...
1
vote
1answer
53 views

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 ...
1
vote
1answer
61 views

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 ...
0
votes
1answer
31 views

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 ...
1
vote
0answers
30 views

Simulation physics software for air blowers [closed]

Anyone know a physics simulation software for air blowers or where you can simulate air lifting objects? I want to simulate a lottery drawing machine.
2
votes
1answer
101 views

How does hydraulic press work at molecular level?

Let's consider the following arrangement: I know that because of conservation of energy the force on the car has to be amplified. The work $W$ done is $$W = \text{Force} \cdot \text{distance} \, ...
0
votes
0answers
21 views

Radiative transfer in a two dimensional slab

I am trying to implement some radiative transfer to a hydrodynamics code. However, all texts that deal with multidimensional radiative transfer assume spherical coordinates, however the hydro code is ...
2
votes
3answers
116 views

Does this dimensioneless quantity have a name?

When studying creeping flows, a common choice for a characteristic pressure scale is $$p_0 = \frac{\mu_0 U_0}{L_0},$$ where $\mu_0$ is a reference dynamic viscosity, $U_0$ is a reference velocity and ...
0
votes
1answer
21 views

Relative magnitudes of pressure gradient force and Coriolis force at midlatitudes

In the midlatitudes, both Coriolis and pressure gradient forces are present in the atmosphere. Can a statement be made about which one of the two forces is bigger in this region?
0
votes
1answer
46 views

If I was to poke two holes in a water filled balloon would it lose water twice as fast a a balloon with one hole?

if I was to assume that the only force behind water coming out of the holes is the pressure i.e., the height of the water remaining which is constantly changing (declining) as water leaves the ...
0
votes
2answers
159 views

Derivation of Viscous Force

For viscous drag, the formula for the force is, $$ \mathbf F=\pm\eta A\nabla\mathbf u $$ where $\eta$ is the viscosity coefficient, $A$ the area and $\nabla\mathbf u$ the velocity gradient. How is ...
1
vote
1answer
54 views

Unsteady Rankine-Hugoniot relations. Is it applicable?

For a unsteady normal shock moving in a medium, the Rankine-Hugoniot relations can be derived, by converting the problem into a steady by fixing the frame of reference on the shock. This idea is easy ...
0
votes
1answer
110 views

Relation between pressure and velocity of a fluid

What is the relation between pressure and velocity of a fluid in a closed pipe flow? I used the Bernoulli equation in case of a pipe having non viscous fluid. The pipe is say tilted at an angle and ...