A Numerical Study for Biomimetic Structures to Control Wall Shear Stress in Water

Abstract

There are numerous practical applications whose operational efficiency depends on the shear stress (skin friction drag) on their functional surfaces, including artificial reefs, artificial hearts, and continuous flow microbial fuel cells. For the most part, the fundamental physics that govern surface shear stress are well understood and established, especially for relatively simple shapes such as a sphere or cylinder. However, the use of passive, bio-inspired, additive structures to control surface shear stress has thus far seen limited investigation. To evaluate the effect of geometrical forms on surface shear stress, 29 biomimetic structures based on sharkskin, cacti, and ocean-dwelling suspension feeders were studied. The structures were modeled in COMSOL Multiphysics, and the shear stresses on their surfaces were studied. The results show that shear stress on the surface of a structure depends not only on surface area, but also on the general form of the structure. In addition, the surface shear stress of some structures display a strong dependence on fluid-flow orientation, while others do not.