Biological flows - Biological surfaces
Biological surfaces exhibit structures which are, at first sight, both appealing and enigmatic. The skin of aquatic animals, the arrangement of feathers on birds' wings or the micro-structured surface of some plants' leaves hold a promise of interesting fluid-dynamic effects.
Over the past 40 years, the attention of researchers has focused on newly discovered properties of biological surfaces, mainly regarding:
- the delay on the onset of transition to turbulence;
- wall friction reduction in turbulent flows;
- separation control devices;
The complexity of this research is in part caused by the number and functions of different biological surfaces found in Nature: from the rigid, porous scales on butterfly wings to the shaggy bristles on bats' skin, from the silky fur of seals to the combined superhydrophobic/superhydrophilic behavior of the leaves of the water fern Salvinia molesta.
Media made up by an elastic solid skeleton and permeated by a fluid are ubiquitous in nature and increasingly seen in technology: examples in nature range from soil to ciliary bed enabling respiratory, circulatory, urogenital and ambulatory functions to surfaces of butterfly wings. In the technological world, analogous composites have been employed both as sensors and actuators in machines, fluidic pumps and nanorod arrays used in DNA analysis.
Our numerical activity in this field is based on a multiscale approach stemming from homogenization theory. It is sponsored by a EU grant and by a major Italian naval company.