Drawing No. EH–FM–028 // Fluid Mechanics & Piping
Vortex Shedding & Resonance Simulator
Reviewed August 2026
A steady flow past a circular cylinder can produce an unsteady sideways force as vortices leave alternately from each side. Tune the flow until the shedding frequency approaches a structural natural frequency, then compare the wake, lock-in band, amplitude trend and Strouhal–Reynolds behavior from one consistent model.
01 // Interactive vortex-shedding lab
Change the flow and structural inputs, then compare every visualization against the same live model state.
Parameters
Sc uses the conventional wind-engineering definition above. The separate M_D index is used only inside the page’s illustrative response envelope. The shaded lock-in window is a visualization centered on frequency matching; this page uses 0.88–1.32 × Ucrit only as a display envelope, not as a universal engineering limit.
Live readout
02 // One model behind every tab
The street, lock-in map and charts now share the same fluid and structural state.
For a fixed circular cylinder, self-sustained Kármán shedding begins near Re ≈ 47. That threshold is not a universal lower limit for fluid–structure interaction: flexibly mounted cylinders can show subcritical VIV.
The same calculated St and fₛ drive the vortex animation, the lock-in map, the operating-point marker and the frequency-matching gauge.
Reduced velocity organizes the response and mass–damping strongly affects its magnitude. The plotted response envelope is illustrative, not a universal amplitude correlation.
03 // Frequency-matching gauge
The compact gauge uses the same uncoupled Strouhal shedding frequency and structural natural frequency as the four tabs above.
04 // Background, assumptions & references
Open these notes when you want the engineering detail behind the animation.
- Roshko (1954) — NACA TR 1191, development of turbulent wakes from vortex streets Classic circular-cylinder experiments covering regular shedding and wake transition.
- Fey, König & Eckelmann (1998) — Strouhal–Reynolds relationship Experimental correlation from shedding onset near Re = 47 to the onset of boundary-layer transition.
- Journal of Fluid Mechanics (2021) — Experimental evidence of VIV at subcritical Reynolds numbers Demonstrates why the fixed-cylinder Re ≈ 47 shedding threshold should not be interpreted as a universal VIV cutoff.
- Journal of Fluid Mechanics (2023) — VIV with high structural damping Shows that lock-in range and response depend strongly on fluid–structure parameters and are not a universal fixed band.
- Wind Energy Science (2026) — engineering VIV model for circular towers Uses the conventional Sc = 4πmζ/(ρD²) definition and reduced velocity U* = U/(fₙD).