Linked Questions
14 questions linked to/from What is (local) pressure within a gas on the microscopic level?
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Gas pressure description [duplicate]
If one googles "gas pressure", one will find many seemingly authoritative sites that say things like "Gas pressure is caused by the force exerted by gas molecules colliding with the surfaces of ...
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How does fire heat air?
I understand that fire heats its surroundings via conduction, convection and radiation. I've read that conduction is nearly irrelevant to this process as air is a poor heat conductor. In descriptions ...
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How does hot air rise?
If a balloon is filled with hot air, it is rising due to buoyancy: the mass of the hot air inside the balloon is lower than the mass of the same volume of the cold air outside the balloon cavity.
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Navier-Stokes Derivation
Someone knows a physical derivation of the Navier-Stokes equation? Mainly the stress tensor. A lot of authors simply "jumps" the stress tensor and it's the more important of physical motion and ...
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Significance of Stokes Hypothesis
When we derive the Navier-Stokes Equation, we come across a a common assumption made by Stokes that makes the two quantities namely Mechanical pressure and Thermodynamic pressure equal to each other.
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Barometric formula / Hydrostatic pressure for an ideal gas
I have recently looked into two different derivations of the Barometric formula, trying to figure out why both of them work: (assuming temperature is constant for all heights)
One is based on the ...
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Collision Term in the Classical Boltzmann Transport Equation
I cannot get over the feeling that in the classical derivation of the collision term of Boltzmann's transport equation molecules that are already knocked out of a $(\textbf r, \textbf v)$ space volume ...
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Knudsen Number and pressure
When computing the Knudsen number to know if the continuum hypothesis can be applied as $\frac{k_B T}{p \sqrt{2} \pi d^2 L}$, do we use the static or total pressure of the free stream? My object is ...
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Is there a general math term for the idea behind the WKB and similar methods that assume slowly varying sources?
Many different physics techniques for approximately solving differential equations seem to follow the same basic pattern. One starts with some differential equation $Df(x) = s(x)$ (or $s(x) f(x)$), ...
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Equilibrium Distribution Function
In kinetic theory, the distribution function $f(\mathbf{x},\mathbf{\xi},t)$ is the generalization of the density $\rho(\mathbf{x},t)$, which represents the density of particles with velocity $\mathbf{\...
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Chapman–Enskog theory and a Noether's invariant of energy?
So in this answer:
Folks figured out thermodynamics before statistical mechanics. In particular, we had thermometers. People measured the "hotness" of stuff by looking at the height of a ...
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Motivation for pressure term in fluid approximation
A common prescription for the momentum flux $J_{ij}$ of a fluid is the following
$ J_{ij} = \rho u_i u_j+p\delta_{ij}-\sigma_{ij} $
where $\sigma_{ij}$ is the viscous stress, $p$ the pressure, $\...
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Pressure of a system at the thermodynamic equilibrium
I'm reading a book in which it says that a system is at mechanical equilibrium if the pressure is constant in time but not necessarily uniform in space at any fixed point (for example it can be caused ...
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Is it possible to use BBGKY hierarchy to convert the collision time in terms of macroscopic variables?
So I'm trying to teach myself BBGKY hierarchy. The notes (page 50) have various time scales associated with different processes:
$$ \frac{1}{\tau_C} \sim \frac{\partial V}{\partial \vec q} \frac{\...
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