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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Mach cone geometry from Mach number

Given a Mach number, how would I go about determining the geometry of the associated Mach cone? Apologies, I'm not too well versed in physics.
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Is it possible to cause condensation in air using low energy pulsed lasers?

I read here that femtosecond pulsed lasers can cause condensation in the air. They primarily work by ionizing air, thereby creating charged hot spots around which water particles condense. But the ...
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Why did the Baker Shot have a normal mushroom cloud instead of a radial blast wave?

The US tested its first underwater nuclear device with the Baker Shot in Bikini lagoon. It was supposed to be identical to the Fat Man device dropped on Japan. However it was measured at 23 kt ...
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Analytical Solution of the Sod Problem with Different Gammas?

Is there a known analytical solution to the Sod Shock Tube problem where the two gases have different specific heat ratios $\gamma$? I have only been able to find solutions where the $\gamma$ values ...
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How does a sound wave behave at a phase transition?

I wonder about the following: A shock wave is propagating from within a solid body outside into a liquid. How will it behave? Especially, will the frequency remain the same?
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What would happen to a shockwave if it transitioned to a fluid with a different density?

Imagine that we can keep two fluids close without mixing too much. They have different densities. Could be water and air, for example, or two liquids floating one on top of each other. What happens if ...
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What Are The Physics and Air Pressure Effects of Extremely Large Bells

How would one go about figuring out the physical properties of when a bell is hit. Can I parameterize the diameter of the bell, its height, and the kinetic force of the knock to get the volume in ...
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What’s the difference between contact discontinuity and shock discontinuity?

Is there an intuitive, mathematical way to understand the difference between contact and shock discontinuities? From the standpoint of hyperbolic PDEs, shocks occur when the characteristic curves of ...
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1answer
57 views

Mach number at the throat of Convergence-Divergence nozzle

Why is it important to have a Mach number=1 at the throat of Convergence-Divergence nozzle? What if the Mach number at the throat is less than 1? Is a modification in the nozzle design required then?
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How is pressure “lost” in a supersonic inlet?

I understand that a shock wave cannot happen in reverse (since you don't get shock waves in nozzles), but what trips me up is this; stagnation (fluid-brought-to-a-stop) pressure decreases in the ...
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1answer
49 views

Derivation of Burgers' equation in sonic boom

I am studyng Burgers equation. In many resources is said that this equation arise in sonic boom model. I' m look for derivation of this equation starting from Navier-Stokes or (Euler). I know that ...
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Is the EMP threat to the power grid supported by physics? [closed]

Every once in a while I come across some article saying that our modern power grid could be knocked out of commission for up to a year by an electromagnetic pulse. I'm skeptical of such warnings. ...
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Specific heat ratio in shockwaves

This is not a homework problem. I am looking for some direction: A normal shockwave occurs in a gas with an unknown specific heat ratio $\gamma$. The static pressure ratio across the shockwave is $10....
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Hydrodynamics shock wave Riemann problem

I'm studying the Riemann problem in hydrodynamics. I've learned that a rarefaction wave and a shock wave will be created. From what I know, a shock wave is a wave which travels at higher speeds than ...
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Is undamped reflection in a pipeline possible, under described circumstances?

Take $\,H_2O\,$ as the compressible medium (water hammer), and if we were to decide to compress it to the limit of breaking down to sub-components, holding in view the non-locallity of protons and ...
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Is it possible to produce shock waves in air using low intensity pulsed lasers?

Air has about 0.04% carbon dioxide. Carbon dioxide has a very strong absorption band around 4.2µm. Let's say I used a nanosecond pulsed 4.2µm MIR source and targeted it into air, part of this would be ...
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Structure of Mach diamonds in supersonic and hypersonic flows (SpaceX raptor engine video of Sept. 28, 2019)

Last night, SpaceX held another show and tell, and there was a nice long, almost 1 minute burn of a raptor engine. The flow stabilized really nicely, and you get an absolutely fantastic view of the ...
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Why is it that sound at standard conditions always travels the same speed?

Say you have a small fire cracker. When it explodes, it imparts some kinetic energy to the surrounding air molecules, and they propagate that kinetic energy outward through collisions. Intuitively, ...
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Newton's cradle faster than light? [closed]

If we have a Newton's cradle toy where the balls actually touch each other. Can energy be transferred from the first ball to the last one faster than the speed of light? And what factors control the ...
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Modal filtering with Vandermonde matrix - Artificial viscosity

I am trying to implement a 2D shock detector for an artificial viscosity model to control strong nonlinearities in compressible fluids. The method I am relying on is originally from: Yu, M. L., ...
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What happens during cavitation?

Cavitation is vapor bubbles and when they implode creates a shock wave, before imploding the bubble can reach temperatures of 10000k. I want to know what conditions must be met to make cavitation, ...
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Do shock waves consider the travel time downwards?

I'm reading this physics book, and in it contains this problem. Quoted: An airplane is flying at Mach 1.75 at an altitude of 8000 m, where the speed of sound is 320 m/s. How long after the plane ...
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120 views

Minimum speed for a mantis shrimp punch to create cavitation?

When a mantis shrimp punches it creates cavitation, because of the speed it creates sudden changes in the water. I want to know how slow can a mantis shrimp punch and still make cavitation? Notes: ...
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What's the difference between shock waves and acoustic waves?

What's the difference between shock waves and acoustic waves? I tried and searched around this subject, but I could not find any relative article about it. Please help me find a proper answer.
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Interstellar medium shock heating

How fast would a hypothetical spacecraft need to get to experience significant heating from interaction with the interstellar medium (ISM)? Significant, in this context, means a steady-state ...
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Shock Wave Initial Condtions

So I am looking for a way to scale a translating shock wave in 1D, whose physics are governed by the Euler equations. Specifically, I would like $\rho_L=r\cdot\rho_R$ where $\rho$ is density, r is ...
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Features of a Jet of Water

Having created a water rocket that operates with compressed air forcing water out through a bottle's nozzle, I was interested in the some of the features of the jet of water that can be seen using ...
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Is $TdS = dU + PdV$ true at very high strain rates? (Thermodynamic equilibrium)

I have read some reports of scientists who are interested in equations of state for unreacted explosives. They want these equations of state to describe the mechanical response of an explosive as it ...
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Shooting a glass made different with water!

I read about an experiment conducted long back ago. The experiment tells that shock waves are the reason for this. The experiment goes like this, shooting a drinking glass with bullet then bullet ...
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Waves generated in an explosion

A cracking furnace exploded in a petrochemical industry building near my city somedays ago. The building is more or less far from the city, and even so people could notice the explosion. The windows ...
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Why is it a sonic “boom” and not a sonic “boooooooooooooooo…m”?

As I understand it, when an object pushes past the sound barrier, a sonic boom doesn't happen just once, but rather, continually (correct me if I'm wrong). So why is it that there seems to be only a ...
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Why an aircraft or a ship produce pressure waves both in front and behind them?

I think it is obvious why a pressure wave is produced in front of a moving object but why the rear of it should produce a wave?
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What makes a bottle full of water soo bouncy?

Let's take a small coke bottle (a plastic one). Now fill the bottle entirely with water not even letting a small air bubble, however we cannot stop forming a tiny bubble. Now this water bottle when ...
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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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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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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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812 views

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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466 views

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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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 ...