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Curle Aeolian Tone & Cylinder Vortex Shedding Noise Calculator

When wind blows across wires, cables, or cylinders, alternating Karman vortex shedding exerts unsteady dipole lift forces, creating singing "aeolian tones".

Wind speed or flow velocity perpendicular to cylinder axis in m/s.

Diameter of cable, wire, or rod in millimeters.

Length of cylinder exposed to airflow in meters.

Dimensionless shedding frequency constant (typically 0.20 to 0.21 for subcritical Reynolds numbers).

Distance from cylinder to listener in meters.

RMS fluctuating lift coefficient from alternating vortex shedding (typically 0.4 to 0.5).

Calculated Result
350.0 Hz

Aeolian Shedding Frequency

Peak Dipole Sound Pressure Level

89.8 dB (re 20 µPa)

Dipole Sound Power Level

97.6 dB (re 1 pW)

Crossflow Reynolds Number

25000

Radiated Acoustic Power

5.793e-3 W

Calculation Breakdown

  1. Vortex Shedding Aeolian Tonef_s = St · U / d = 0.21 × 25 / 0.015 = 350.0 Hz
  2. Curle Dipole FormulationDipole acoustic radiation from unsteady surface pressure fluctuations: 89.8 dB
  3. Aeroacoustic IntensityU⁶ scaling predicts rapid noise elevation with increasing wind speed

What Is the Curle Aeolian Tone & Cylinder Vortex Shedding Noise Calculator?

An aeolian tone is the musical whistling or humming sound produced when wind blows past telephone wires, suspension bridge cables, or automobile antennas.

Curle (1955) extended Lighthill’s theory to show that solid boundaries in flow introduce acoustic dipole sources scaling with the 6th power of velocity (U⁶), far exceeding quadrupole noise at low Mach numbers.

How Does the Curle Aeolian Tone & Cylinder Vortex Shedding Noise Calculator Work?

Flow separation behind a blunt cylinder forms an alternating von Kármán vortex street.

Each shed vortex induces an equal and opposite fluctuating lift force on the cylinder surface, acting as an acoustic dipole radiating sound perpendicular to the flow.

Curle Aeolian Tone & Cylinder Vortex Shedding Noise Calculator Formula & Variables

The core mathematical equation utilized by this calculator is expressed as:

f_s = St · U / d, W_dipole = (π · ρ₀ · U⁶ · d · L · C_L²) / (12 · c₀³)

Computes Strouhal vortex shedding frequency and Curle’s aerodynamic dipole sound power scaling with the 6th power of velocity (U⁶).

How to Use the Curle Aeolian Tone & Cylinder Vortex Shedding Noise Calculator

  1. Input wind speed and cylinder diameter to determine the pitch of the tone.
  2. Specify cylinder length and listener distance to calculate Sound Pressure Level (SPL).
  3. Use helical strakes or fairings if shedding tone creates annoying noise or structural fatigue.

Step-by-Step Example Calculation

15 mm Power Cable in 25 m/s Wind

Input Values:

crossFlowVelocityMps:25
cylinderDiameterMm:15
cylinderLengthMeters:1
strouhalNumber:0.21
observerDistanceMeters:10
fluctuatingLiftCoefficient:0.45
Worked Steps: Predicts aeolian singing tone at 350 Hz and distinct dipole sound radiation.

Understanding Your Result

Shedding frequency fs (Hz) indicates the exact musical pitch of the tone.

Peak SPL (dB) occurs at 90° to the wind direction, where dipole radiation is maximized.

Factors That Affect the Result

  • Diameter d: Thinner wires shed vortices at higher frequencies (higher pitch); thick bridge cables produce low-frequency thrumming.
  • Velocity U: Frequency scales linearly with wind speed; sound power scales with the 6th power (U⁶).

When Should You Use This Calculator?

  • Assessing whistling noise on automotive roof racks and antennas.
  • Predicting vortex-induced acoustic noise and vibration in heat exchanger tube bundles.

Assumptions & Limitations

  • Valid for uniform crossflow in the subcritical laminar boundary layer regime (300 < Re < 10⁵).

Frequently Asked Questions

Calculation Accuracy & Reference Note

Standard aeroacoustics benchmark model.

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