Name: Hydrodynamic
Uploaded: 2026-10-09T19:27:15.000Z
Duration: PT14.750S
Channel: PTKAME
Description: PTKAME shorts video about Hydrodynamic

Hydrodynamic

PTKAME

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I've been watching saba stream and I couldn't find... show more

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17,210 görüntüleme • 4 ay önce

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31,557 görüntüleme • 3 ay önce

even though I was busy, I still manage to... show more

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81,921 görüntüleme • 4 ay önce

Anyways here's what I was talking about - Recently... show more

PTKAME

23,022 görüntüleme • 5 ay önce

By adding a secondary subharmonic forcing, bouncing droplets on... show more

Physical Review Fluids

29,207 görüntüleme • 8 ay önce

"But where's the flash?" Watch this CNN demonstration of... 6g of PETN being ignited by open flame. What happens? The PETN burns with a visible flame for several seconds. Then it detonates. The detonation happens so fast there is no visible flash — the camera goes straight from fire to debris field. And here's the key: the fire that WAS there is blown OUT by the blast wave. This is not a shaped charge. This is unconfined PETN in open air. No flash. No fireball. The blast wave actually extinguishes the existing flame. Why? Three reasons: PETN's reaction zone is measured in microns and completes in nanoseconds (Anderson et al., Propellants Explosives Pyrotechnics, 2022). At gram scale, the entire detonation event is over in single-digit microseconds. A 30fps camera captures 33,000 μs per frame. The event occupies <0.03% of one frame. The visible "flash" people expect from explosions comes from compression-heating of surrounding air — not the explosive itself. At gram scale there simply isn't enough gas volume being heated to produce visible light that registers on a standard camera. In a shaped charge, it's even less visible because the energy is directed INTO the target as a hydrodynamic metal jet (Munroe effect), not radiated outward as heat and light. The Hezbollah pager attacks (Sept 2024) used 3-6g PETN per device. Watch the CCTV footage — no fireballs. Just a pop and casualties. Sandia National Labs detonates ~32mg PETN and researchers stand next to the chamber in safety glasses. No flash. No fire. "No flash = no explosive" is a Hollywood education, not a physics one. Joe Rogan shawshow more

Jon Bray

25,456 görüntüleme • 6 ay önce

This looks like a simple transparent shock absorber filled... with oil. But what you are seeing is one of the most destructive phenomena in fluid engineering. This is cavitation in its true form. The white cloud forming beneath the piston is not foam and it is not air. The oil is literally changing from liquid to vapour at room temperature. When the piston moves rapidly, the oil is forced through tiny passages inside the damper. The fluid velocity increases, the local pressure drops, and if it falls below the oil's vapour pressure, the liquid begins to boil without any increase in temperature. The moment the pressure recovers, those microscopic vapour bubbles collapse almost instantly. And that is where the real damage begins. The destructive forces of cavitation is really not understood well by most. A collapsing cavitation bubble creates shockwaves and high-speed microjets that strike nearby surfaces with enormous local forces. Repeated millions of times, these tiny implosions can slowly eat away hardened metals, destroy precision components and reduce the lifespan of expensive machinery across industries. This same invisible phenomenon is one of the biggest challenges in naval engineering. Ship propellers operating under enormous loads can suffer cavitation erosion, losing efficiency while creating underwater noise. For advanced stealth submarines, that noise can become a major problem because cavitation can reveal their position. Decades of research have gone into specialised propeller designs, pump-jets, surface finishes and hydrodynamic optimisation to delay its formation. The same issues affects hydroelectric turbines that convert the energy of entire rivers into electricity, and industrial pumps that move oil, chemicals and water through critical infrastructure around the world. Perhaps the most remarkable part is that after 4-5 decades of advances in metallurgy, coatings and manufacturing, engineers still cannot simply build a material that is immune to cavitation. The solution is not to make stronger metals forever. It is to understand the fluid dynamics so precisely that cavitation is prevented before in those destructive bubbles ever form.show more