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Questions tagged [shock-waves]

A shock wave is the final stage of a nonlinearly steepening wave that has reached a balance between steepening and energy dissipation resulting in a discontinuity.

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First law of therodynamics appiled across a normal shock

This is a snippet from the book Compressible Flow by Anderson. Here, he is trying to evaluate the change in entropy across the shock using the relation, $s_2 - s_1 = c_p \ ln \frac{T_2}{T_1} - R \ ln ...
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Fuel efficiency of supersonic planes

I stumbled upon an interesting plot; in particular, the dependence of wave drag on the Mach number: It is curious to see that the drag coefficient drops so abruptly in the supersonic regime, but I am ...
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Physical reason behind the origin of shock waves in astrophysics [duplicate]

Shock waves arises in astrophysics in accretion flows and in winds. But we know that shock waves usually occurs in supersonic flows when the flow encounters any obstacle or when the properties of the ...
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Importance of speed of sound in astrophysical flows

The speed of sound is very important in astrophysics in the study of accretion and wind flows. I have two questions as follows: What is special about the speed of sound and not any other value of ...
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Calculation of force when shock wave passes

According to the Rankine–Hugoniot equation, the pressure P2 after the shock wave passes is $$\frac{P_{2}}{P_{1}}=\frac{2 \gamma M_{1}^{2}}{\gamma+1}-\frac{\gamma-1}{\gamma+1}$$ Does this indicate ...
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Qualitative difference between shockwave and circular waves in electromagnetism

We know that a charged particle moving at uniform speed does not radiate. However, when travelling sufficiently fast in a medium, the build up of wavefronts cause a shockwave to form, which we observe ...
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Is it possible to hear a nuclear blast first from the ground, and afterwards through air?

Since a mechanical wave travels faster in the solid, and if you were able to put your ear on the ground, on the same surface that the bomb hit, would you hear the shockwave first from the ground? Does ...
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Standing waves in raptor rocket engine test

Stopping the video of the recent test of the raptor rocket engine, one can see a standing wave forming in the exhaust gases: https://youtu.be/MAAzbjG_Duc?t=23 I was wondering what might cause a ...
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How do we get supersonic bullets?

I recently answered a question on the WorldBuilding forum about grenades and bullets. One of the things that came up was that I argued smokeless powder in a rifle round could detonate, but was ...
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How does a sonic jet attenuate a sound wave?

Let's assume air flows through a pipe and exits into free atmosphere. The atmospheric pressure is below the critical pressure of the flow, hence the gas is accelerated and a sonic jet forms at the ...
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Effect(s) of different species in shock waves

In air, transitioning from a local mach number ($M$) of $M > 1$ to $M < 1$ produces a shock. But $M$ is defined simply based on the velocity of an object relative to the local speed of sound. If ...
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Physical reasoning behind hearing a single shock

When an object is flying in the air at a mach number ($M$) greater than 1, a shock wave is continuously produced and the mach cone makes a particular angle, $\theta_M$, with the ground (or normal). An ...
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Shock waves at $M = 1$ and $M > 1$

When a wave moves faster than the local speed of sound ($c_s$) in a fluid, there is a shock wave since the fluid is unable to respond to the moving wave. Even if velocity ($v$) is constant, if ...
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How do you explain the formation of shockwave on the wing surface during near sonic flight?

Explanations of shockwave for the common folks (youtube videos, googling) all tend to focus on successive sound waves generated by the air craft traveling outward in circles (sphere). That to me, ...
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Theoretical models of short Gamma Ray Bursts

I have recently been interested in the currently known theory behind short gamma ray burst (sGRB) models. I can't seem to find any available source which shows the theory behind the relativistic shock ...
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How to get exact solution to Sod shock tube test?

I wrote a program in Fortran which calculates Sod shock tube numerically. Now I want to compare it with exact (analytical) solution, but I don't know how to get it. Can I find it somewhere or do I ...
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Sonic Boom in Aircraft and Spacecraft

I would like to know why aircraft, and spacecraft produce a double sonic boom on breaking the sound barrier. A while ago, I thought I got it, as there’s a start and finish point to every vehicle. ...
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Intuitive explanation of supersonic flow behavior?

It is well known that once the flow of a gas becomes supersonic, it behaves very differently to subsonic flow: Velocity increases as flow area increases. Velocity decreases along a pipe with friction....
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Supersonic wind tunnel with total pressure loss?

I am reading "I am reading "Fundamentals of Aerodynamics" 5th edition, J.D.Anderson. If you have the book, go to chapter 10: Compressible Flow through Nozzles, Diffusers, and Wind Tunnels". In order ...
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How are detached shocks formed?

If I have an object moving faster than the local speed of sound (which to my understanding is a phase velocity) how is it possible that the phase fronts are able to pile up at a distance away from the ...
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Derivation of average momentum change in diffusive shock acceleration

I am trying to figure out a specific step in the derivation of the power law spectrum for cosmic ray particles upon diffusive shock acceleration. I am working with Drury 1983 (pdf link) but I have ...
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How can you protect yourself from an acoustic shock wave?

To protect your electronics during a huge Electromagnetic Pulse in the RF range, all one needs is a Faraday shield for the most part. On the other hand, what do you do when you are near an acoustic ...
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Moving faster than speed of sound in material

Throughout my schooling this year, one thing that came up was that materials have a speed of sound. That concept makes sense to me. To my understanding it's the speed at which force can propagate ...
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Bulk viscosity in jump conditions for shock waves

One of the jump conditions for shock waves can be derived from the Navier-Stokes equation and it takes the form (see Shu, Gas dynamics, p.212) $\dfrac{d}{dx}\left(\rho u^2 + P - \frac{4}{3}\mu \frac{...
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Can I use calculus to calculate how fast a the cracker of a whip is moving when it cracks?

So I know that when a whip cracks it is breaking the sound barrier and makes a sonic boom. I understand that this is Because of conservation of momentum as the whip tapers in thickness and hairpins at ...
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Do massless particles create tiny gravity-booms?

So just a precursor, my main focus is math and I don't fully understand everything in physics so I apologize if this has an obvious answer or the wrong tags are used. That being said, I do know that ...
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Why were the sonic booms produced by the landing SpaceX side boosters audible on the ground?

Supersonic vehicles produce Mach cones behind them, which observers hear as sonic booms as they pass by. So if, for example, a jet goes supersonic as it heads toward you, but decelerates to subsonic ...
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Two sonic booms colliding

If I theoretically created an experiment where I could create two sonic booms in directions such that the sonic "nose" is facing each other; what would happen? more specifically: Lets suppose I have ...
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Why exactly do atomic bombs explode?

In atomic bombs, nuclear reactions provide the energy of the explosion. In every reaction, a thermal neutron reaches a plutonium or a uranium nucleus, a fission reaction takes place, and two or three ...
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Entropy variation produced by a shock wave

I'm studying Compressible Fluid Mechanics through the book "Fluid Mechanics", 4 ed., by Frank White. I learnt that a shock wave is an irreversible process that occurs in the flow. Because of that, I ...
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Can Normal Shock Waves be stationary in a flow?

When solving problems of converging diverging nozzles, a shock wave is formed in the flow. For the purpose of problem solving we consider it to be stationary in one point of the flow. Is this ...
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after the reentry of the side booster rockets of the Falcon heavy, why was the sonic boom heard?

what is the underlying principle of this boom here? did the boosters landed with speed greater than the sound barrier ? And they were heard after some time they both landed , how is that possible? is ...
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Thermodynamics - 'Internal irreversibilities' in a fluid (gas) across a shock wave

I'm struggling to understand(in an 'intuitive way') how it is possible to have, in a control volume, a stagnation pressure loss(adiabatic and isentropic slow down to zero velocity) without a change in ...
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what is the relationship between the velocity of a wave source and the amplitude of a shock wave?

I'm having trouble understanding the kind of interference leading to shock wave formation and how it relates to the velocity of the wave source.I came across this image: It illustrates the formation ...
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Shockwaves speed through rarer and denser atmosphere

I was going through the different speed of sound through different atmospheric/air conditions and the Newton-Laplace equation gives $ c=\sqrt{\frac{\gamma P}{\rho}} $ So, where does the ...
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Can you “rewind” sound messages by going supersonic? [duplicate]

I was having a discussion with a friend about supersonic flights. It was then when he proposed an idea on an interesting experiment that can be done during a supersonic flight. The experiment goes ...
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What happens to a supersonic shockwave if the object stops?

Just wanted to ask what would happen to a supersonic shockwave if the object creating it suddenly stopped, for example a bullet. In the image attached I would expect to hear the supersonic crack of ...
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Does a teapot burst more easily when filled with water? [closed]

This question arises from an (unlucky) incident at home. My family then went on arguing over whether our teapot would still exist in one piece if it had been empty, instead of filled with hot water. ...
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Why are shock waves irreversible?

As far as I know ordinary waves do not change the entropy of the gas, whereas shock waves do. Could someone please explain the reason behind this difference?
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Types of shockwaves

I understand that there are different types of shockwaves formed when aircraft fly at supersonic speeds, namely oblique, normal and bow. I also understand that normal shockwaves form on the top of ...
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What are the properties of a sonic shock wave?

An aircraft travelling faster than sound creates a shockwave. How dense is the air in this shockwave, and how thick is the shockwave? Is this a range or a definite number? I realize the shockwave ...
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How is the equation of Mach number derived?

Wikipedia states that for a pitot-static tachometer, the mach number for subsonic flow equates to $$M = \sqrt{5\left[\left(\frac{p_t}{p_s}\right)^\frac{2}{7}-1\right]}.$$ How did they get to that ...
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Which factors affect the frequency of a sonic boom?

Does the shape or speed affect the frequency of a sonic boom and if so in what way? Is the frequency of a sonic boom always the same? If so, what frequency is it and why is it that frequency?
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Would a major electromagnetic pulse (EMP) leave most cars operable?

According to C. Davis of the Ask a Prepper blog, after a major electromagnetic pulse: Most electronics will be fried beyond repair and it will be years – in some cases decades – before anyone is ...
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Nonlinear waves equations derivation from Navier-Stokes

In my professor's lecture notes, I came across the next approach of studying non-linear waves in fluids. So we have compressible Navier-Stokes and continuity equation in 1D and we assume adiabatic ...
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What causes the expansion and implosion of the medium before an explosion?

I often see in slo-mo explosions, whether underwater or in air, the medium expanding outward before imploding, at which point the flash of the explosion happens. I used to think this was a cool movie ...
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Sod shock tube - Contact Discontinuity

sorry for bothering with my question. https://en.wikipedia.org/wiki/Sod_shock_tube I have trying to understand, how is it possible to have a discontinuity on Density and not on Pressure. I don't ...
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What makes a fusion reaction an “explosion”?

The Lawrence Livermore National Laboratory just put out a bunch of movies of atomic bomb detonations. How does the nuclear reaction generate the destructive shockwave that can be seen? If it just ...
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Can a sonic boom put out a fire?

Since a sonic boom is just a collection of pressure waves combined into one massive pressure wave, would the low pressure zone behind it be enough to put out a large fire?
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How is a shock wave a wave?

I've recently started learning Physics using University Physics (Fourteenth Edition) and I've come to the subject of (sound) shock waves. It's explained in the case of an aircraft travelling at ...