Quasi‐2‐D Forces on a Vertical Cylinder in Waves

Abstract

Prediction of the total force on a vertical cylinder in waves has been investigated. Drag and inertia coefficients on a small section of span have been measured for a range of orbital shapes. There is considerable scatter but rms in-line force is in reasonable agreement with U-tube data unless orbital shape approaches circular when local and total force is markedly overestimated on a quasi-2-D basis. For surface Kc less than about 12 lift is predominantly at twice the wave frequency. A quasi-2-D calculation using U-tube data underestimates total force for deep-water waves and in general lift prediction is somewhat unreliable.