🌪️ 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 = 1.05 Hz (T = 0.952 s)

Regime: Supercritical (Disrupted Shedding)

St = 0.280

Cylinder Reynolds Number (Re_D) 569,444 Strouhal St = 0.2800

Fluctuating Lift Force (RMS) 46.12 N/m C_L,rms = 0.10

Vortex Streamwise Spacing (a) 1214.3 mm a/D = 3.04

Vortex Street Width (h) 341.2 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                 : Offshore Subsea Pipeline Ocean Current Vortex Shedding
Cylinder Diameter (D)      : 400.00 mm (0.4000 m)
Free-Stream Velocity (Uinf): 1.50 m/s (q_dyn = 1153.12 Pa)
Fluid Properties           : rho = 1025.000 kg/m3, mu = 1.0800 cP
-----------------------------------------------------------------
REYNOLDS NUMBER (Re_D)     : 569,444.4
STROUHAL NUMBER (St)       : 0.2800
SHEDDING FREQUENCY (fs)    : 1.050 Hz (Period = 0.9524 s)
Wake Flow Regime           : Supercritical (Disrupted Shedding)
Fluctuating Lift Force     : 46.12 N/m span (CL_rms = 0.10)
Vortex Street Dimensions   : Spacing a = 1214.3 mm, Width h = 341.2 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