Another Real World Science question...

[seawasp]

... I'm trying to find information -- preferably text with an accompanying diagram/image mapping things out -- on how the propagation of a blast wave works in the presence of an object such as a human being caught in it. Naive assumption on my part would imply that what you'd get is a high-pressure ridge on the portion facing the blast, with a lower pressure area on the other side, but that it's possible another, high-pressure shock could result ON the opposite side due to the shockwave pressure being delayed and channeled around the object, to meet in opposition on the other side and producing a secondary shock-ridge.

I've found papers on various aspects of blast physics and so on, but none that give me the overall look at what happens around an object like that caught in a blast.

(like the prior ones, these are questions springing from proposal research I'm doing)

Comments

[shana.livejournal.com]

These were the most promising looking links from the first 2 pages of a search on Google Scholar.

http://www.bordeninstitute.army.mil/published_volumes/conventional_warfare/ch07.pdf

http://www.jtrauma.com/pt/re/jtrauma/abstract.00005373-199603001-00006.htm;jsessionid=KthB6Snft89fD1G0kFJwjvd1Xbt38vH2dm1Jzgylw2mZshlBr5TG!-1260103914!181195628!8091!-1

http://www.ramcjournal.com/2001/wounds_of_conflict/cullis.pdf

http://www.ramcjournal.com/2001/wounds_of_conflict/horrocks.pdf

http://www.fimnet.fi/sjs/articles/SJS42005-279.pdf

If they're not helpful, let me know and I'll try to refine the search.

[seawasp]

Unfortunately, those all tell me about the biophysical effects of being IN a blast, but not about the actual propogation of the blast wave AROUND the body and how it interacts. I'm not interested in the damage it does to a person, that's secondary; I'm looking for the pressure/acceleration found at various points around an object caught in a blast, and how the front, back, and sides differ from each other in the pressures they encounter.

[anton-p-nym.livejournal.com]

Perhaps NASA would have something along the lines of shock wave propogation around a high-speed/high-altitude parachutist that you could adapt.

-- Steve's also thinking that this'd be prime Doc Edgerton territory, but is uncertain how to unearth this sort of stuff.

[shana.livejournal.com]

That's a lot harder to find.

These seem to be talking about inanimate objects; I don't know whether you'll find them useful.

http://alexandria.tue.nl/repository/books/637345.pdf

http://www.springerlink.com/content/062u2r67g0282120/

http://www.mne.psu.edu/psgdl/Shockwaves.pdf

http://books.google.com/books?hl=en&lr=&id=TGGZjHvfqLAC&oi=fnd&pg=PA109&dq=blast+propagation+front+back+object&ots=WZaDeqYMdF&sig=qqzsxAqDMfecPw__4TwrWy0nSBY

That's all I have time for at the moment.

[mouser.livejournal.com]

It might also create a vacuum effect, or be negligible.

Blast physics are pretty strange. It's one of those that you spend a career on. It depends on the type of explosion, force of the blast, amount of explosive, distance, shape of the object, etc, etc, etc.

Is this for something specific?

[seawasp]

A092-109.

[mouser.livejournal.com]

Um... What? (Honestly, that topped the Google search!)

OH! ARMY092-109

Umm... I don't think there is anything like what you're looking for. The problem is that it's a chaos system and there are a TON of ancillary variables that can have a HUGE effect, to stay nothing of the fact this is an effect over time.

[seawasp]

Whoops, mis-labeled, it's A092-110

I know enough to know that I don't know enough.

[qinshihuangdi.livejournal.com]

Pressure, fluid motion, and dynamics are a bit of a pain. I could say what would happen to a truly rigid massless object, but realistic objects are always more difficult. Especially as I do not have a thorough background in blast physics, just a bit of dynamics and fluid mechanics. Irregular, nonhomogenous objects are always more difficult to accuratly model. Mind if I pass this on in the Kratskeller and Doc's Inn?

[kayshapero]

No idea, but I'm getting increasingly curious about the proposal. :)

(Now why do I keep thinking of Remo Williams?)

[seawasp]

Blast Dosimeter.

[midnightlurker.livejournal.com]

Well, Remo would just move in such a way that the blast wave somehow managed to miss him. ^.^

[seawasp]

Which would be useless for my application; the blast front would act as though no one was there, which isn't a practical outcome...

[kayshapero]

Naw, he'd just riiide the shockwave to the next county/country/planet. :)

[sorek.livejournal.com]

No clue but now you've got me singing three "The Who" songs plus the theme song to NCIS.

[sub-musashi.livejournal.com]

I'll bet a straightforward diffraction calculation would give you a good first order approximation. But that's going to be a crazy turbulent system, so you'd probably have to just go in and measure it with Schlieren methods or similar.

[qinshihuangdi.livejournal.com]

Thing is, if you are talking about human bodies there is a real shortage of usable prisoners and legal environments conducive to such experimentation, especially if one wants to study a comprehensive set of postures.

[seawasp]

Crime labs and the Mythbusters solved that problem a long time ago. Buster volunteers again!

[sub-musashi.livejournal.com]

Well, I'd assume that the body holds together structurally and that the transmitted wave is negligible, and just use a mannequin for the first try.

[seawasp]

Unfortunately, this doesn't help me, as I have neither time nor resources nor knowledge that would be needed to conduct such an experiment....

[sub-musashi.livejournal.com]

How accurate are you looking for? Can you just model the body as an elongated cylinder? The calculations for that are do-able, and are probably already available in a textbook somewhere. I can't recall the classic text on shock propogation, and I'm away from my old notes...

[seawasp]

A general outline of the variance to be expected is good enough. I don't need detail, but order-of-magnitude estimates of how the blast profile seen at, say, the front of the chest would be different from that seen at the small of the back, or at either side, would be very nice.

[sub-musashi.livejournal.com]

I just looked at the project. Ugh. This is going to be tough. Are you hoping to have a blast wave model that you'll match up to the mesured pressure around the helmet? The shocks are going to be so dependent on angle and shape that it's going to be really messy. Can you put a detector strip all around the circumference of the helmet so you get some omnidirectional sensing?

[seawasp]

That's part of what I need to know; how many sensors, of what type, and what sensitivity, I will need to get the needed data. I don't actually need to ANSWER this right now, but it'd be nice to have a plot/image that shows "see, the differences around the body are extreme and thus you can't do it with one point sensor, you'll need (fill in my solution)." Images are preferred because in proposals, one picture is worth a page or two of text because people will almost always look at the pictures but may skip the text.

[sub-musashi.livejournal.com]

Hmm, how about this (sorry, I'm not sure what page this link will take you to): http://books.google.com/books?id=ApAqBlpSTtIC&pg=PA991&lpg=PA991&dq=shock+wave+pattern+around+cylinder&source=bl&ots=LNhUhvxmOT&sig=-Ss2JK2cX5uAMvOKIzyZAqoOFHA&hl=en&ei=zrIuSpuMHJ3GM7C12PgJ&sa=X&oi=book_result&ct=result&resnum=10#PPP1,M1

It's got lots of nifty pictures.