Set by the source's compactness and Mach number — linear acoustics

• A distorted inflow gives back the tone more blades took away — acoustic far field — Bessel functions of the tone's argument; six blades · noise-scaling
• A wire sings with the force on it, not the flow round it — any frequency; kr is the only parameter · noise-scaling
• More blades hush a propeller only while its tips are slow — acoustic far field of any rotating source; the argument is n M sin θ · noise-scaling
• The boom that turns back before the ground — any Mach number above one, 0 to 20 km — no wind · nonlinear-wave
• The largest bulk viscosity is the first to expire — linear acoustics; carbon dioxide at the surface pressure of Mars, its relaxation scaled by pressure · noise-scaling · hero
• The largest bulk viscosity is the first to expire — linear acoustics; carbon dioxide at the surface pressure of Mars, its relaxation scaled by pressure · noise-scaling
• The sound now is the source then — a source in a straight line, subsonic — acoustic · what-a-gas-carries-forward
• The sound now is the source then — steady straight-line motion, uniform atmosphere — acoustic · what-a-gas-carries-forward
• The sound that only leaves — linear acoustics, uniform medium at rest — any Reynolds number · noise-scaling
• Nothing but the shape of the gap — a thin film — the clearance here is 1.0e-3 of the bore · bearing-film
• Nothing but the shape of the gap — a thin film — the clearance here is 1.0e-3 of the bore · bearing-film
• The sound is what does not cancel — linear acoustics, kd = 0.01 — a compact source, and the observer at rest · noise-scaling · hero
• The sound is what does not cancel — linear acoustics, kd = 0.01 — a compact source, and the observer at rest · noise-scaling
• The sound is what does not cancel — linear acoustics, kd from 0.02 to 0.2 — compact sources, and the observer a wavelength out · noise-scaling
• The viscosity nobody uses — linear acoustics, kd from 0.02 to 0.2 — compact sources, and the observer a wavelength out · noise-scaling
• The sound is what does not cancel — linear acoustics, kd = 0.1 — a compact source, and the observer at rest · noise-scaling
• A wire sings with the force on it, not the flow round it — Strouhal 0.2, correlation length 4 diameters · noise-scaling · hero
• A wire sings with the force on it, not the flow round it — subcritical cylinder, Strouhal 0.2 · noise-scaling
• A wire sings with the force on it, not the flow round it — Strouhal 0.2, correlation length 4 diameters · noise-scaling
• A wire sings with the force on it, not the flow round it — Strouhal 0.2, rms lift coefficient 0.45, correlation length 4 diameters — measured values, borrowed · noise-scaling
• The sound is what does not cancel — kd = 0.3 — compact sources at rest · noise-scaling
• The sound now is the source then — kd = 0.3 — compact sources at rest · noise-scaling
• The sound that only leaves — kd = 0.3 — compact sources at rest · noise-scaling
• The viscosity nobody uses — linear acoustics, kd = 0.3 — a compact source, and the observer at rest · noise-scaling
• The sound is what does not cancel — compact sources, kd ≤ 0.32 — the acoustic analogy's small-Mach limit · noise-scaling
• The sound that only leaves — compact sources, kd ≤ 0.32 — the acoustic analogy's small-Mach limit · noise-scaling · hero
• The sound that only leaves — compact sources, kd ≤ 0.32 — the acoustic analogy's small-Mach limit · noise-scaling
• The boom that turns back before the ground — Ma 1 to 3 — standard atmosphere, no wind · nonlinear-wave
• The boom that turns back before the ground — Ma 1 to 1.3 — wind linear in height · nonlinear-wave
• The bubble that hammers — cavitation well past inception — 1.0 bar, and the model's own limit · bubble-collapse
• The sound is what does not cancel — a 1 m jet into still air at c = 340 m/s · the coefficient is borrowed · noise-scaling
• The sound is what does not cancel — a 1 m jet, c = 340 m/s · the acoustic coefficient is borrowed · noise-scaling
• The sound that only leaves — a 1 m jet into still air at c = 340 m/s · the coefficient is borrowed · noise-scaling
• The sound that only leaves — a 1 m jet, c = 340 m/s · the acoustic coefficient is borrowed · noise-scaling
• The boom that turns back before the ground — Ma 1.1 to 2 at 11 km — no wind · nonlinear-wave · hero
• The boom that turns back before the ground — Ma 1.1 to 2 at 11 km — no wind · nonlinear-wave
• A boom is aged in the thin air it starts in — design margin 1.25; Ma 1.8 — geometrical acoustics and the inviscid Burgers age along each ray; standard atmosphere, 15 km, no wind, no absorption · nonlinear-wave
• The boom that turns back before the ground — Ma 1.3 to 2 at 15 km — no wind · nonlinear-wave
• The boom that turns back before the ground — Ma 1.3 to 2 at 15 km — no wind · nonlinear-wave
• The edge is a rumble, not a quieter bang — Ma 1.3 to 2.5 — linear acoustics, a standard atmosphere, 15 km · nonlinear-wave · hero
• The edge is a rumble, not a quieter bang — Ma 1.3 to 2.5 — linear acoustics, a standard atmosphere, 15 km · nonlinear-wave
• A boom is aged in the thin air it starts in — Ma 1.8 — geometrical acoustics and the inviscid Burgers age along each ray; standard atmosphere, 15 km, no wind, no absorption · nonlinear-wave · hero
• A boom is aged in the thin air it starts in — Ma 1.8 — geometrical acoustics and the inviscid Burgers age along each ray; standard atmosphere, 15 km, no wind, no absorption · nonlinear-wave
• A boom is aged in the thin air it starts in — Ma 1.8 — geometrical acoustics and the inviscid Burgers age along each ray; standard atmosphere, 15 km, no wind, no absorption · nonlinear-wave
• The edge is a rumble, not a quieter bang — Ma 1.8 — linear acoustics, a standard atmosphere · nonlinear-wave
• A wire sings with the force on it, not the flow round it — car aerial, 6 mm, 0.7 m, 30 m/s, at 2 m; still air at c = 340 m/s · noise-scaling
• The bubble that hammers — cavitation well past inception — 10.0 bar, and the model's own limit · bubble-collapse
• A boom is aged in the thin air it starts in — geometrical acoustics and the inviscid Burgers age along each ray; standard atmosphere, 15 km, no wind, no absorption · nonlinear-wave
• A boom is aged in the thin air it starts in — geometrical acoustics and the inviscid Burgers age along each ray; standard atmosphere, 15 km, no wind, no absorption · nonlinear-wave
• A boom is aged in the thin air it starts in — geometrical acoustics and the inviscid Burgers age along each ray; standard atmosphere, 15 km, no wind, no absorption · nonlinear-wave
• A boom is aged in the thin air it starts in — geometrical acoustics and the inviscid Burgers age along each ray; standard atmosphere, 15 km, no wind, no absorption · nonlinear-wave
• Oxygen makes a boom's crack, nitrogen its rise time — acoustic: still air at 20 °C and 1 atm, relaxation from ISO 9613-1; a plane shock, no turbulence · nonlinear-wave · hero
• Oxygen makes a boom's crack, nitrogen its rise time — acoustic: still air at 20 °C and 1 atm, relaxation from ISO 9613-1; a plane shock, no turbulence · nonlinear-wave
• Oxygen makes a boom's crack, nitrogen its rise time — acoustic: air at 20 °C and 1 atm · nonlinear-wave
• Oxygen makes a boom's crack, nitrogen its rise time — acoustic: still air at 20 °C and 1 atm, relaxation from ISO 9613-1; a plane shock, no turbulence · nonlinear-wave
• Oxygen makes a boom's crack, nitrogen its rise time — acoustic: still air at 20 °C and 1 atm, relaxation from ISO 9613-1; a plane shock, no turbulence · nonlinear-wave
• Oxygen makes a boom's crack, nitrogen its rise time — acoustic: still air at 20 °C and 1 atm, relaxation from ISO 9613-1; a plane shock, no turbulence · nonlinear-wave
• The sound now is the source then — closest approach 100 m, sound speed 340 m/s — acoustic · what-a-gas-carries-forward
• A distorted inflow gives back the tone more blades took away — acoustic far field, still air at c = 340 m/s; 1.88 m propeller, 2 kN, 127 kW, heard at 30 m · noise-scaling · hero
• A distorted inflow gives back the tone more blades took away — acoustic far field, still air at c = 340 m/s; 1.88 m propeller, 2 kN, 127 kW, heard at 30 m · noise-scaling
• A distorted inflow gives back the tone more blades took away — acoustic far field, still air at c = 340 m/s; 1.88 m propeller, 2 kN, 127 kW, heard at 30 m · noise-scaling
• A distorted inflow gives back the tone more blades took away — acoustic far field, still air at c = 340 m/s; 1.88 m propeller, 2 kN, 127 kW, heard at 30 m · noise-scaling
• A distorted inflow gives back the tone more blades took away — acoustic far field, still air at c = 340 m/s; 1.88 m propeller, 2 kN, 127 kW, heard at 30 m · noise-scaling
• A distorted inflow gives back the tone more blades took away — acoustic far field, still air at c = 340 m/s; 1.88 m propeller, 2 kN, 127 kW, heard at 30 m · noise-scaling
• A wire sings with the force on it, not the flow round it — any wire, c = 340 m/s; a vibrating one lengthens Λ · noise-scaling
• More blades hush a propeller only while its tips are slow — acoustic far field, still air at c = 340 m/s; 1.88 m propeller, 2 kN, 127 kW, heard at 30 m · noise-scaling · hero
• More blades hush a propeller only while its tips are slow — acoustic far field, still air at c = 340 m/s; 1.88 m propeller, 2 kN, 127 kW, heard at 30 m · noise-scaling
• More blades hush a propeller only while its tips are slow — acoustic far field, still air at c = 340 m/s; 1.88 m propeller, 2 kN, 127 kW, heard at 30 m · noise-scaling
• More blades hush a propeller only while its tips are slow — acoustic far field, still air at c = 340 m/s; 1.88 m propeller, 2 kN, 127 kW, heard at 30 m · noise-scaling
• More blades hush a propeller only while its tips are slow — acoustic far field, still air at c = 340 m/s; 1.88 m propeller, 2 kN, 127 kW, heard at 30 m · noise-scaling
• More blades hush a propeller only while its tips are slow — acoustic far field, still air at c = 340 m/s; 1.88 m propeller, 2 kN, 127 kW, heard at 30 m · noise-scaling
• More blades hush a propeller only while its tips are slow — acoustic far field, still air at c = 340 m/s; 1.88 m propeller, 2 kN, 127 kW, heard at 30 m · noise-scaling

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