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

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How does this help an aeroplane to fly? [duplicate]

I read it somewhere on the internet that wings of an aeroplane are designed in such a way, that they increase the velocity of air above the wings and so pressure above the plane becomes less than the ...
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3answers
118 views

Spontaneous motion in a wind tunnel

Suppose that a hollow truncated cone is placed in a wind tunnel with a steady wind speed $V$. The cone is placed in such a way that it's base of area $A_1$ faces the wind (rather than the other side ...
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3answers
180 views

pressure in fluid mechanics of incompressible liquid

Most liquids can be approximated to be incompressible, since the Mach-number is much smaller than 1. That means that the density variations are negligible and from the relation between pressure p and ...
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1answer
106 views

Acceleration of particles in a pipe with variable cross section

I am currently making an exercise from Paterson,1983, IV.3.ii. It goes as follows Water flows steadily and incompressibly along a pipe whose area cross section $A(x)$ varies slowly with the ...
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51 views

Is there a consensus on the definition of wavelength for a solitary wave?

Solitary waves are by definition a wave of single nature so the usual definition for periodic waves does not apply. R. Dalrymple provides a definition but I saw a lot of other websites and papers ...
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99 views

Formula for residence time/turnover rate with unsteady state

I'm not sure this is the correct place to ask my question... but maybe someone could still help me. I'm looking for a way to calculate the residence time/turnover rate. I have the production and ...
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106 views

Plotting Dividing Streamline

I'm trying to plot just the dividing streamline of a flow on Maple. I have the complex potential $$\Omega(z)=Uz+\frac{m}{2\pi}ln(z)$$ with Stream function $$\psi(r,\theta)=Ur\sin\theta + ...
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81 views

What field of physics play a major role in water pipe function [closed]

Background: I'm a legal MMJ patient and I've been looking into water pipers/bongs recently. I understand that this question can be a little controversial but where I live this is all legal as long as ...
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1answer
91 views

liquid polymers of high molecular weight

We often see a limit of melting point as a function of polymer chain length. Polyethlyene tops at about 190C, and polyethlyene glycol saturates at only 67C no matter how long the chain is: ...
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44 views

Variance and Intermittency in turbulence

In the turbulent transport of a scalar field, $\Phi$, decomposed into mean and fluctuating components, $\Phi=\left<\Phi\right>+\phi^\prime$, the scalar variance is defined as ...
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95 views

Time required to fill a pipe line

This is quite embarrassing to ask, but I haven't done a fluid flow calculation in a very long time and when you don't use it, you lose it! I have a natural gas pipeline that I want to purge of air ...
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53 views

Closed pipe/sound resonance sound type sound coming from mineral processing plant

I work near a very large mineral processing plant which does vibrate our building and there is also a sound/feeling very similar to the closed pipe/sound resonance that is achieved when opening a back ...
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2k views

Flow Rate and Orifice Diameter

I have a electrical/electronics background and have limited knowledge of Fluid Mechanics. So, i will try to be as clear as possible. I am currently working with brake fluid in an ABS system and to ...
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147 views

Projectile motion of the water surface from water discharging from a pipe

I am looking at pipe flow into a pit. How do I calculate the outside water surface path. I understand how to calculate projectile motion from calculus in terms of a velocity, point object and ...
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1answer
130 views

May I know how a vortex tube works? [duplicate]

From my point of view, high gas pressure input creates air rotation inside the tube. Due to the rotation, the kinetic energy in the air change to internal energy. The internal energy release as heat ...
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46 views

Nonlinear waves and shock formation

In the cases of nonlinear acoustics, why is shock formation unlikely when the dispersion is strong when compared to the nonlinearity of the wave?
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38 views

Nuclear Weapon Effects: Cloud Rise [closed]

I am interested in modeling the rise of a nuclear cloud to stabilization height post detonation. I am interested in any ideas you may have on the approach. I have collected some research on the topic ...
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124 views

Horizontal Capillary Question

I have a fluid mechanics question, that I think is caused by a lack of understanding of some key concepts. Suppose we have a horizontal capillary with a radius of 10um. The fabrication process has led ...
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141 views

Efficiency estimation for small-scale (~15cm) propellers

First up, apologies if this isn't quite the place for this; Aerospace is still in Area 51 so there doesn't seem to be a better place for it. If it helps, feel free to give theoretical answers and I'll ...
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163 views

What is the drag coefficient of an open wedge?

To check my two dimensional CFD calculation I am looking for reference data on the drag coefficient of an open wedge. The geometry is shown below, together with the flow direction. I have found ...
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854 views

From Navier–Stokes equations to Euler, Bernoulli, etc [closed]

How can one go from the 3D compressible Navier-Stokes equations to the simpler Euler equations, Bernoulli's equation and other fluid dynamic equations?
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77 views

What causes a whirlpool to form in a bathtub? [duplicate]

I mean, when you have a full bathtub and then let it empty, under what conditions does a whirlpool form? Could we devise an experiment and measure this effect? When it comes to fluids, I don't know ...
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22 views

Windflow in a car [duplicate]

When driving on a highway, if the front two windows of a car are open , how does the air flow in and out of the windows? Clearly, air cannot keep accumulating inside the car, so how/where does the air ...
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108 views

Leakage rate Calculation

I have to calculate leak rate for helium/air from an enclosure which is made of fabric. This is similar to helium balloons. There are small holes in the fabric. How should i proceed ?
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38 views

Bulk transport of an aerosol by a blast wave

I'm trying to model the behaviour of aerosols in response to blast waves. (This is for visual effects.) Intuitively, if a flare left a smoke trail above a field and then a bomb detonated elsewhere ...
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61 views

Can a hierarchy of fixed points potentially be used to describe a kinetic energy spectrum which is composed of multiple scale invariant subranges?

Making use of a nonequilibrium functional renormalization group (Berges and Mesterhazy, 2012) are able to investigate a whole hierarchy of fixed points that explain the successive evolution of a ...
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82 views

What is the domain of validity of the Omega equation?

The Omega eqation is used in meteorology for estimate the value of the vertical velocity. Considering that the horizontal velocity field and density is given by observation. Under which condition ...
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100 views

virtual air-surface temperature difference above a water body

I'm trying to work through the equations for the following paper: http://onlinelibrary.wiley.com/doi/10.1029/2009JD012839/abstract and am trying to understand the concept of virtual air temperature, ...
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146 views

How to find outflow pressure/force of air through a pipe

I have been trying to find the correct method for determining the outflow force resulting from a certain amount of air being forced into a pipe of a certain dimension. Essentially i'm trying to ...
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51 views

Books describing motion of objects in fluid [closed]

I'm looking for any resources that would help me model the behavior of objects moving in fluid. My end goal is to be able to describe the motion of irregularly shaped objects in a river environment. ...
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1answer
316 views

Force required to move a fluid out of piston at depth

I have a cylinder filled with water in it at the bottom of the ocean. Say 100 meters down. In this cylinder is a piston that moves up and down. Its job is to squish the water out the bottom of the ...
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98 views

What temperatures can be reached in an air-to-air thermocompressor nozzle and why?

People are generally of the opinion that the boiler injector cannot be redesigned to run on air. In other words, an air-to-air thermocompressor that puts fresh air into a tank without a mechanical ...
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115 views

Physical interpretation of an intermittency definition

A random function $v(t)$ is said to be intermittent at small scales of its "Flatness" $F$, given as $$ F(\Omega) = \frac{\langle (v_{\Omega}^{>}(t))^4\rangle}{\langle ...
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47 views

blood fluidics - can you determine the force exerted on a bound red blood cell under shear stress?

Is it possible to calculate the force exerted on a bound, infected red blood cell under various shear stresses? The strength of an adhesive interaction is normally measured by SPR or AFM, however ...
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37 views

where to find sample fluid stirring data?

I want to find some force data for fluid stirring. Originally I intended to record the data using my force sensor, but it doesn't have the resolution to read stirring force for Newtonian fluid. ...
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176 views

Wall pressure of a fluid flow in a pipe of variable radius

Using all cylindrical coordinates, pipe with z-axis vertically upward and radius of $r = G(z)$, flow is incompressible, inviscid and steady, Using appropriate boundary conditions I want to find the ...
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1answer
4k views

Determine viscosity using falling sphere (Stokes Law, Ladenburg correction)

Introduction I am trying to determine the viscosity of a fluid. Therefore, I let a sphere of known mass m and radius r fall ...
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58 views

Is sonoluminescence relevant to the behaviour of Navier-Stokes (or converse)?

More precisely, could Sonoluminescence be a singularity of Navier-Stokes(NS)? Is there some other connection that might be interesting, or is it completely irrelevant? Wiki page mentions NS, but says ...
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65 views

Does Bernoulli's principle hold in moving reference frames? [duplicate]

Possible Duplicate: Bernoulli’s equation and reference frames Sometimes in train, when setting behind opening window, I can feel strong gale blowing in. The closer to the window the ...
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161 views

Mechanical effects of convective flow in steady-state stagnant film diffusion

When analysing diffusion problems in the context of the simplified film model, two limiting cases are ussually introduced during the solution of the differential chemical species mass balance ...
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280 views

Venturi in nozzle of water jet

I am trying to understand a waterjet system for maneuvering boats from a physics perspective. (See Marine Holland Parts if you are interested.) The system uses venturis in the nozzles. My question is ...
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121 views

How does a particle move in Water?

Is there any precise model (More precise than the random walk model) that describes a particle's movement in water ?
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240 views

Why is my ballpoint pen spatially temperamental?

I'm trying to write with a ball-point ink pen on a plastic[1] sandwich bag. When I try to write on some parts of the bag, no ink transfers to the bag: I can continue trying for quite a while in vain. ...
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2answers
548 views

How is energy transferred from one incompressible fluid to another?

When you apply pressure to an incompressible fluid the pressure is transferred. If you stop applying the pressure there is no motion. Volume and density are integral parts of calculating how much ...
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69 views

The sound of coffee [duplicate]

Possible Duplicate: Why does the sound pitch increase on every consecutive tick at the bottom of a filled cup of coffee? A colleague suggested this experiment this morning : Get a cup of ...
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43 views

What is the fluid approximation for BCS action?

For a system with free fermion gas at finite density (i.e. free Dirac action), we have an ideal fluid description with rho, p, n. What is the fluid description for BCS action? Suppose we have a box ...
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119 views

How to integrate twice of this viscous term?

I am reading a paper, and I do not understand why the author said the following term when integrated twice will become, $\int\limits_\Omega {{\rm{d}}\Omega {{\bf{\psi }}^{\bf{u}}}\cdot\nabla ...
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126 views

Can a the volume flow through a positive displacement pump be reliably measured by tracking revolutions of the drive shaft? [closed]

The question refers to non-compressible fluids. I'm mostly thinking about monopumps (excentric screw pumps), but this also should apply to any type of gear pumps as well, possibly also to piston ...
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1answer
271 views

Boundary condition for water waves generation

I am trying to model water wave propagation in 2D with CFD. What would be a suitable boundary condition to generate the waves on the left boundary? Currently I vary the fraction of water above the ...
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53 views

Why tea dust in a cup of tea seems to concentrate in the bottom center? [duplicate]

Possible Duplicate: Vortex in liquid collects particles in center Sorry for my bad English. :-) Hello ! Here is my question : If you enjoy some cup of tea, you may see that there are some ...