Talk:Shock wave

An "everyday example" would be a balloon popping or something, not the A-Team.  :-) - Omegatron 17:51, May 13, 2004 (UTC)

Actually, I found that example clear, understandable, and relevant; a balloon shock wave has little actual effect, as opposed to the clearly visible shock wave in the A-Team. Meelar 17:53, 13 May 2004 (UTC)

This irked me too, it just seemed like a lame example. Replaced "is from the TV series The A-Team (or any other action series or movie). When handgrenades are thrown at the bad guys they are supposedly blown away, flying through the air, by the blast waves of the grenades." with an example almost everyone is familliar with: a sonic boom.--Deglr6328 01:49, 17 Jul 2004 (UTC)

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"There are two basic types of shock waves: blast waves and driven waves."

Which one is an aircraft? - Omegatron 13:22, Jul 22, 2004 (UTC)

shocks around bodies moving through fluid tend (like aircraft) would probably be categorized as driven waves,

although that distinction (blast/driven) tends to refer to unsteady, one-dimensional configurations.

mach wave

i'm surprised the most common type of shockwave, the mach wave (sound wave), is not mentioned in the article. it is an infintely weak shock. 141.211.174.250 23:00, 8 Nov 2004 (UTC)

friction

"When meteors enter the earth's atmosphere, this phenomenon causes them to heat up and disintegrate; this is sometimes erroneously attributed to friction." I'm not sure I really understand the difference. If air molecule hit the survace and each other they heat up. If they hit each other in shock wave they heat up. Wouldn't both of these actions called friction? --Gbleem 00:32, 19 Nov 2004 (UTC)

(someone correct me if I go astray). Gbleem: Strictly speaking, you are correct, except the difference is that fluid friction is usually only understood to mean lateral transfer of mean momentum by collisions between atoms, whereas shock waves and other drastic processes tend to also have friction associated with other kinds of molecular motion besides translation (in particular, rotation, which is where bulk viscosity comes from). In a sense, shocks are dissipative, "friction"-driven processes. These processes are mostly identifiable within the shock thickness itself, which is only a few molecular mean free paths thick (tens of microns). The reason saying "friction heats up a re-entering meteor" is misleading is that frictional heating is mostly due to the shearing action between adjacent layers of fluid moving along a body (like in a boundary layer) and is caused by velocity gradients in shear layers of far greater thickness than molecular mean free path. However, a blunt body like a meteor has a shock wave standing off it. By the time any fluid reaches the meteor, it has already been slowed down tremendously by the shock wave and is already very hot. Viscous dissipation at the meteor's surface will be small compared to the heating already done by the shock. Further, shock waves, though physically speaking are accompanied by viscous processes within them, are caused by drastic changes in pressure and can actually be accurately described (macroscopically) by the Euler equations which govern inviscid fluid flow. It's just that to these equations (and to most observers) the shock appears to be an infinitely thin discontinuity.

soliton

I don't think so. Usual definition of soliton is a smooth self-reinforcing waveform; a shock wave is a discontinuity.