Frequency Calculation Excel Sheet — Wake

1. Theoretical Background When a fluid (wind or water) flows past a cylindrical structure, vortices alternately shed from each side, creating a periodic force. The vortex shedding frequency (( f )) is given by:

| Re range | Strouhal number | |----------|----------------| | < 1e5 | 0.18 | | 1e5 – 3.5e6 | 0.20 | | > 3.5e6 | 0.22 | wake frequency calculation excel sheet

| Parameter | Value | |-----------|-------| | Mass per length (kg/m) | 200 | | Damping ratio ζ | 0.005 | | Log decrement δ | =2 PI() B9 | | Scruton number | =(2 B8 B10)/(B11*B2^2) | Diameter (m) | f_shed (Hz) | Resonance

| Velocity (m/s) | Angle (deg) | Proj. Diameter (m) | f_shed (Hz) | Resonance? | |----------------|-------------|--------------------|-------------|-------------| | 5 | 0 | 0.5 | 2.0 | OK | | 10 | 0 | 0.5 | 4.0 | RESONANCE | | 15 | 30 | 0.5 | 6.0 | OK | vortices alternately shed from each side