Nonlinear Flow of Wave Crests Past a Thin Pile

The measured pattern of peak water line around a vertical circular pile in periodic wave action can disagree with wave-scattering theory, showing a nonlinear dependence on incident wave height when the pile radius is very small compared to the wavelength. The peak water line was measured around piles of several diameters in relatively shallow water with various incident laboratory waves. Features of the patterns indicate that a disturbance like a ship's bow wave forms during peak crest flow when a certain Froude number, incident crest velocity head divided by pile radius, becomes large, on the order of 0.1—1.0. The laboratory tests shoudl reproduce basic flow effects in situations of coastal and ocean engineering interest, because field and lab situations have the same Froude number, implying geometric flow similarity.