On the drag reconfiguration of plates near the free surface

Identifier:  imarina:5874092

Handle: https://hdl.handle.net/20.500.11797/imarina5874092

Authors:  Satheesh, Sukruth; Huera-Huarte, Francisco J

Abstract:
© 2019 Author(s). Rectangular foils of different flexural rigidities were towed normal to the flow at a fixed speed in a quiescent fluid in order to study the effect of the proximity of the upper edge of the models to free surface. It was found that flexibility ensured drag reduction due to the reconfiguration process at all submergence depths, with certain foils exhibiting depth-independent behavior. The study of Vogel exponents also showed that a sublinear or even a depth independent relationship between drag and velocity can be attained at specific flexural rigidity values. A modified classical beam theory model using a power-law based load distribution was utilized to obtain an empirical relationship between the loading exponent and Cauchy numbers and to identify the foil tip location. Particle image velocimetry was also undertaken to interpret and further understand the force results. The experiments showed the existence of 2 ranges of Cauchy numbers with a small degree of overlap in ranges wherein the drag coefficient and Vogel exponents are independent of submergence depth.