Difference between blast & shock wave

In summary, a blast wave is the initial pulse from an energetic explosion, while a shock wave is a longer-lasting effect. A blast wave is simply a strongly peaked shock wave, so you're on the right track. Propagation of a shock or blast wave is dependent on the mean free path between particles in the medium through which it travels. The mean free path is another way of saying how far apart particles are on average. In the vacuum of space, the mean free path can be quite huge - not unlike an enormous billiard table with only a few balls. Plasma effects tend to dominate under these circumstances.
  • #1
Jain_Mor
3
0
Hi guys and gals,

with respect to SNRs (or anything for that matter)

What is the difference between a shock wave and a blast wave?
Is it just that a blast wave is a sharp peak in the change in variables, where as a shock wave has a region behind it in which the variables gradually decrease?

Also read that the Sedov-Taylor or Self-Similar phase of an SNR is a blast wave, does this mean the other phases aren't?

Many thanks in advance, its confusing quite a lot of us.
 
Astronomy news on Phys.org
  • #2
A blast wave is the initial pulse from an energetic explosion. It is simply a strongly peaked shock wave, so you're on the right track. Propogation of a shock or blast wave is dependent on the mean free path between particles in the medium through which it travels. The mean free path is another way of saying how far apart particles are on average. In the vacuum of space, the mean free path can be quite huge - not unlike an enormous billiard table with only a few balls. The time between collisions can be lengthy. The individual collisions can result in highly energetic photon emissions, but, lack the systemic kinematical effects of shock waves in a denser medium. Plasma effects tend to dominate under these circumstances.
 
  • #3
Are you speaking relative to SNRs?

Is it possible that a Blast Wave is a Shock Wave whose rarefaction has caught up with the shock front? Thereby giving it a distinct peak?
 
  • #4
Jain_Mor said:
Is it just that a blast wave is a sharp peak in the change in variables, where as a shock wave has a region behind it in which the variables gradually decrease?

I didn't make that much of a distinction between the two when I did my dissertation, but a blast wave is when you put all of the energy at one point and then you get a very nice easy to solve equation.

Also read that the Sedov-Taylor or Self-Similar phase of an SNR is a blast wave, does this mean the other phases aren't?

Yes. Suppose you have a shock wave that goes out for 0.1 light years. At that point you can model it as a smooth uniform gas in which someone dumped a massive amount of energy at one point, and the numbers work out since the size of the original star is much, much smaller than the area you are looking at. Since the star is a "point" the math becomes really simple.

Now if you try to model the shock wave when it is deep inside the star you can't do that.
 
  • #5
Jain_Mor said:
Is it possible that a Blast Wave is a Shock Wave whose rarefaction has caught up with the shock front? Thereby giving it a distinct peak?

I don't think that works. There really isn't much in the way of rarefaction.
 
  • #6
Thanks TwoFish, that's great :)
 

1. What is the difference between a blast wave and a shock wave?

A blast wave is a type of shock wave that is created by an explosion or other sudden release of energy. A shock wave, on the other hand, can be caused by a variety of events, such as a supersonic aircraft or a meteor impact. Both types of waves are characterized by a sudden increase in pressure and velocity, but the source and magnitude of the energy release differ.

2. How does a blast wave differ from a shock wave in terms of propagation?

A blast wave typically travels at a slower speed than a shock wave, as it is created by a localized explosion rather than a continuous force. Additionally, a blast wave typically dissipates more quickly as it travels through the surrounding medium, whereas a shock wave can maintain its intensity over longer distances.

3. Are blast and shock waves both dangerous to humans?

Yes, both blast and shock waves can be dangerous to humans. The primary danger from a blast wave is due to the sudden increase in air pressure, which can cause physical damage to the body and internal organs. A shock wave can also cause physical damage, but it is often the secondary effects of the shock wave, such as debris and flying objects, that pose a greater threat.

4. How do scientists measure the intensity of a blast or shock wave?

Scientists use a variety of instruments to measure the intensity of a blast or shock wave, including pressure gauges, velocity meters, and seismometers. These instruments allow for the measurement of factors such as peak pressure, duration, and impulse, which can help determine the potential impact of the wave on its surroundings.

5. Can blast and shock waves be controlled or mitigated?

While the energy release of a blast or shock wave cannot be controlled, there are measures that can be taken to mitigate their effects. For example, buildings and structures can be designed to withstand the force of a blast or shock wave, and protective barriers can be used to redirect the wave's energy away from vulnerable areas. In some cases, warning systems and evacuation plans can also help minimize the impact of these waves on human populations.

Similar threads

Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
20
Views
2K
  • Astronomy and Astrophysics
Replies
1
Views
1K
  • Engineering and Comp Sci Homework Help
Replies
1
Views
2K
  • Atomic and Condensed Matter
Replies
4
Views
2K
  • MATLAB, Maple, Mathematica, LaTeX
Replies
3
Views
2K
Replies
6
Views
2K
Replies
4
Views
2K
  • Introductory Physics Homework Help
Replies
8
Views
6K
  • Introductory Physics Homework Help
Replies
1
Views
8K
Back
Top