Analyses of drag on viscoelastic liquid infused bio-inspired patterned surfaces

The villi structures found in intestinal tract, infused with mucus, can attain different configurations by elongation and lashing movements. The present work analyzes the different configurations of villi separately and the associated drag behavior that may aid in movement of food through the tract. Using numerical simulations, the variation of drag in intestinal tract with respect to different configurations, especially the inclination of villi, has been studied, with quasi-steady approximations that consider the villi as solid objects. Extending this intestinal tract surface with villi and mucus, to a normal ridge textured surface infused with a viscoelastic fluid, significant changes in drag, owing to the viscoelastic nature of the infused fluid, have been found. The extent of drag reduction or drag enhancement, which is dependent on texture of the surface, is also found to be contingent on rate of deformation of the viscoelastic fluid along the patterned surface, and the density of ridges or solid fraction. Such control over drag on these surfaces, through Weissenberg number and texture of the surface, indicates the possibility of using viscoelastic liquid infused engineered surfaces for bio-medical and industrial applications.