🌪️ von Kármán Vortex Shedding (Strouhal Frequency)

Determine cross-flow cylinder vortex shedding frequency (fs in Hz), Strouhal number (St), fluctuating lift force, and vortex street dimensions (h/a = 0.281).

⚡ Fortran 90 Engine Double Precision (IEEE 754) ✓ ISO / ASME Validated

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👁️ Consultations 29

⚡ Calculs faits 23

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📅 Mise en service Jun 2026

⏱️ Latence < 1 ms

🌪️ Cross-Flow Cylinder & von Kármán Vortex Street Wake

Real-time visual simulation of periodic alternating clockwise and counter-clockwise vortex core shedding

📝 Configuration & Presets

🏭 Industrial Stack (1.2m) 🌊 Subsea Pipeline (400mm) ⚡ Power Cable Aeolian Humming 🚰 Heat Exchanger Tube (20mm)

📐 Cylinder Diameter & Flow Velocity

Cylinder Diameter D [mm]:

Free-Stream Velocity U_∞ [m/s]:

💧 Fluid Physical Properties

Fluid Density ρ [kg/m³]: Air: ~1.2 kg/m³, Water: ~1000 kg/m³

Dynamic Viscosity μ [cP]: Air: ~0.0182 cP, Water: ~1.0 cP

Strouhal Vortex Formulations:
• Strouhal Number: St = (f_s · D) / U_∞ ≈ 0.198 (1 − 19.7/Re)
• Shedding Frequency: f_s = (St · U_∞) / D [Hz]
• Fluctuating Lift: F′_L,rms = ½ ρ U_∞² D · C_L,rms [N/m]
• Stable Spacing Ratio: h / a ≈ 0.281

📊 Vortex Shedding Results

📊 Output Summary
💾 Fortran Source

Vortex Shedding Frequency (f_s)

f_s = 63.27 Hz (T = 0.016 s)

Regime: 🌪️ Subcritical Turbulent Wake Street

St = 0.198

Cylinder Reynolds Number (Re_D) 13,231 Strouhal St = 0.1977

Fluctuating Lift Force (RMS) 0.34 N/m C_L,rms = 0.35

Vortex Streamwise Spacing (a) 107.5 mm a/D = 4.30

Vortex Street Width (h) 30.2 mm h/a = 0.281

📈 Shedding Frequency f_s (Hz) vs Flow Velocity U_inf (m/s)

📉 Strouhal Number (St) vs Cylinder Reynolds Number

=================================================================
 THERMOFLUIDCALC — VON KARMAN VORTEX SHEDDING REPORT
=================================================================
Case Title                 : Overhead Power Line Aeolian Wind Humming Vibration
Cylinder Diameter (D)      : 25.00 mm (0.0250 m)
Free-Stream Velocity (Uinf): 8.00 m/s (q_dyn = 38.53 Pa)
Fluid Properties           : rho = 1.204 kg/m3, mu = 0.0182 cP
-----------------------------------------------------------------
REYNOLDS NUMBER (Re_D)     : 13,230.8
STROUHAL NUMBER (St)       : 0.1977
SHEDDING FREQUENCY (fs)    : 63.266 Hz (Period = 0.0158 s)
Wake Flow Regime           : 🌪️ Subcritical Turbulent Wake Street
Fluctuating Lift Force     : 0.34 N/m span (CL_rms = 0.35)
Vortex Street Dimensions   : Spacing a = 107.5 mm, Width h = 30.2 mm (h/a = 0.281)
=================================================================

📘 Calculation Methodology & Strouhal Standards

Strouhal Shedding Law

Above $Re_D \approx 47$, laminar boundary layer separation becomes unstable, shedding regular alternate vortex pairs into the wake with non-dimensional frequency $St$:

                    fs = (St · U∞) / D
                

Vortex-Induced Vibration (VIV)

Periodic pressure imbalance from alternating vortex shedding exerts fluctuating cross-flow lift forces that can cause destructive resonance in chimneys, marine risers, and tubes.

Key Engineering Assumptions

Uniform steady 2D cross-flow past smooth circular cylinder.
Subcritical turbulent boundary layer separation ($Re_D < 2\times 10^5$).
von Kármán stability spacing ratio $h/a \approx 0.281$.

ThermoFluidCalc Engineering Report