Questions tagged [fluid-dynamics]
The quantitative study of how fluids (gases and liquids) move.
18 questions from the last 30 days
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Are misters (sprays/atomisers) fundamentally limited by the air pressure?
This question is motivated by whether it is physically possible to have a high-quality mister for cooking oil that does not require a non-reusable pressurized can.
A household spray (as in the picture ...
- 175
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Why does flowing water produce what sounds like white noise?
Why does flowing water produce what sounds like white noise? Is this due to a certain type of turbulence? Is there a proof that the noise produced is white (or pink or Brown?)?
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Curious about entropy and information theory in Bohmian mechanics
I've been playing around with Bohmian mechanics in electronic systems. I really like the interpretation of particle trajectories in terms of the continuity, Hamilton Jacobi equation and guiding ...
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Trouble understanding the boundary conditions for the Blasius boundary layer equation
In Section 7.2.1 of Bergman's Fundamentals of Heat and Mass Transfer, there is a derivation of the Blasius equation
$$ 2 \frac{\mathrm d^3 f}{\mathrm d \eta^3} + f \frac{\mathrm d^2 f}{\mathrm d \eta^...
- 137
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How to find pressure in pipe contraction for compressible high speeds flow?
Air with density ρ, absolute pressure P1 flows through a pipe with velocity v₁ and cross-sectional area A₁, and then enters a contraction with area A₂. A1/A2=10. We need to determine the pressure P₂ ...
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Does the no-slip boundary condition contradict Bernoulli's equation here?
Imagine inviscid, incompressible steady-state fluid flow around a cylinder like in the diagram below so that it flows around the cylinder symmetrically about the x-axis:
According to the no-slip ...
- 121
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4
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Temperature of flowing water
Water's temperature is given by (average K.E. of molecules) $=3/2 \ k_{B}T$, so my intuition is that flowing water molecules will gain additional kinetic energy from flowing, leading to a huge ...
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Has someone ever obtained a relative trajectory being exactly the Coriolis formula without a background centripetal force (as gravity)?
In geophysics and many other cases, the Coriolis formula is clearly linked to a background centripetal force.
Read Anders Persson (UK MetOffice, EU ECMWF, Sweden SMHI, Uppsala) https://scholar.google....
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Fluid in a rotating cylinder: how is this wrong?
I have recently been working a bunch of hydrostatic problems with accelerating fluids of all kinds. I came across the classic problem of finding the shape of the free surface of a fluid in a rotating ...
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What pressure is used in Bernoulli's equation in fluid-dynamics?
Hereinafter, the term “fluid” will be used to mean “ideal fluid” (i.e., an incompressible fluid without friction).
The fluid flows to the right through a horizontal pipe at a speed $v$. Then Bernoulli'...
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Could cometary non-gravitational acceleration be linked to surface cohesion transitions?
In several comets, including the interstellar comet 3I/ATLAS, a non-gravitational acceleration is observed, i.e., a net thrust not fully accounted for by gravity. While outgassing is known to produce ...
- 101
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Why do we have to invoke interfacial displacement in solving the Kelvin-Helmholtz instaility?
Lately I've been studying the Kelvin-Helmholtz instability (KHI) and Rayleigh-Taylor instability (RTI). To be specific, in the incompressible limit.
The equations are the same:
\begin{align}
\frac{\...
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Reconciliation of filtering operation in turbulence
I am studying turbulence more specifically properties of filtering operations given by
$$
U(x, t) = \int_{\mathbb{R}^n} G(r, x) U(x-r, t) dr
$$
with normalization condition
$$
\int_{\mathbb{R}^n} G(r, ...
- 61
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How long can electrohydrodynamic (EHD) propulsion last?
In an electrohydrodynamic (EHD) propulsion, I know that there is a thin wire with high voltage (emitter) and a 0-voltage collector. Because of the radial electric field around the thin wire, electrons ...
- 507
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2
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Which orientation of a truncated cone will drain faster?
A container is shaped like a truncated cone (frustum) as in cylinder-like shape where one end has a larger radius than the other. Both orientations contain the same volume of water, and the outlet ...
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