Patent ID: 8684040

Claim:
A system for reducing vortex induced forces on a bluff body disposed in a fluid, the fluid moving relative to the bluff body, said system comprising: said bluff body having a surface, said bluff body being shaped to define a linear body dimension being the largest linear dimension of a cross section of said bluff body in the plane of the flow of the fluid, said bluff body being moveable in at least a direction generally perpendicular to the flow of the fluid; and a plurality of roughness zones disposed on said surface, each of said plurality of roughness zones defining a roughness height extending above said surface that is less than or equal to 5% of said linear body dimension, said plurality of roughness zones modifying the flow of the fluid to suppress fluid induced motion of said bluff body in the direction generally perpendicular to the flow of the fluid, wherein each of said plurality of roughness zones comprises a base and a grit, said grit being disposed on said base.