Determination of the Normal Fluid Load on Inclined Cylinders from Optical Measurements of the Reconfiguration of Flexible Filaments in Flow

Reconfigured flexible filaments exposed to steady fluid load were investigated using a novel non-contact optical technique to measure the normal fluid force due to the fluid loading on inclined cylinders for Reynolds numbers from 25 to 460: a range not covered in previous studies that is of relevance in drag reduction and energy harvesting applications. The ranges of the buoyancy number and the Cauchy number covered in the tests were 3.6×10⁴≤ B ≤2.1×10⁶ and 7.6×10⁴≤ Ca ≤1.4×10⁷. These newly generated data were then used to assess and extend the validity of existing prediction methods for the normal fluid force at low Reynolds numbers. New prediction methods for the equilibrium inclination angle and for the fluid dynamics load were developed for small Reynolds number applications, based on extrapolating existing theoretical results for marine vegetation.