Quote:
Originally Posted by DonDavis
Agreed. The geek is strong over there. A Ham radio guy was chatting about wavelength stuff and resonance.
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He wrong but he is in the right direction. I expect the scouring is due to the velocity point where cavitation starts to occur. When water increases in velocity, the static pressure in that area is reduced. If it moves fast enough, the pressure drops to the point the water boils, making a bubble. The bubble blocks water, which slows it down, increasing pressure and the bubble collapses. Water then hammers the spot where the bubble was.
We run into the opposite of this in high pressure gas releases. The "layered" look is actually real. At each boundary is actually a sonic pressure drop. If the pressure is high enough, you get multiple mini sonic booms, shockwaves. It is one of the reasons "jet" engines are very loud. The newer designs, high bypass turbofans, you push lots of fast air, but the thrust is not above the speed of sound.
