Pressure Wave from Rapid Balloon Expansion

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SUMMARY

The discussion focuses on modeling the pressure wave generated by the rapid inflation of a balloon, particularly when the temperature of the air inside the balloon increases faster than the pressure can equilibrate with the outside environment. The user seeks methods to calculate the frequency power spectra of the resulting pressure wave, considering approaches such as determining the velocity of the balloon membrane and utilizing the pressure wave Green's function. The conversation also draws parallels to shock wave phenomena, indicating a need for simpler solutions in this context.

PREREQUISITES
  • Understanding of thermodynamics, specifically the ideal gas law (PV = nRT).
  • Familiarity with wave mechanics and pressure wave propagation.
  • Knowledge of Green's functions in the context of wave equations.
  • Basic principles of shock waves and their characteristics.
NEXT STEPS
  • Research the mathematical modeling of pressure waves using Green's functions.
  • Explore shock wave theory and its applications in fluid dynamics.
  • Study the dynamics of balloon inflation and membrane behavior under rapid temperature changes.
  • Investigate experimental methods for measuring pressure wave frequency power spectra.
USEFUL FOR

Physicists, engineers, and researchers interested in fluid dynamics, wave propagation, and thermodynamic processes related to rapid gas expansion.

firedancer414
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Hello physics forum,

I'm interested in modeling the pressure wave created due to the rapid inflation of a balloon. Say I'm able to rapidly increase the temperature of the air in a balloon, faster than it can equilibrate its pressure with the outside air. It will expand to satisfy PV = T, and radiate a pressure wave. I'm interested in calculating the frequency power spectra of this pressure wave.

What is the best way to solve for this? One way I can think of is to solve for the velocity of the balloon membrane as it expands, but I'm not sure how I would calculate the membrane velocity. I also thought that I might just be able to use the pressure wave Green's function, and integrate that over the volume of increased pressure.

Please help! Thanks =)
 
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Upon further reflection, this bears resemblance to a shock wave. With this context in mind, is there some simple solution?

I work primarily with optics, I feel like a fish out of water! References, anything would be much appreciated =)
 
Read about Fermi's measurement of the Trinity Site blast in
http://www.cfo.doe.gov/me70/manhattan/trinity.htm
"Probably the most mundane response of all was Fermi's: he had calculated ahead of time how far the blast wave might displace small pieces of paper released into it. About 40 seconds after the explosion, Fermi stood, sprinkled his pre-prepared slips of paper into the atomic wind, and estimated from their deflection that the test had released energy equivalent to 10,000 tons of TNT. "
fermi was about 10,000 meters away.
 
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