École Nationale Supérieure de
Techniques Avancées

Abstract

This internship mainly focuses on the ability of certain organisms such as mosquito larvae to breathe underwater. Several insects breathe using a 'snorkel' but different mechanisms to secure the air supply exist. Firstly, the snorkel of some organisms has a sort of crown of hairs at its end. When the insect swims down, the hairs bend and are able to catch a bubble of air. This allows the organism to go on breathing underwater. Secondly, there is another system made of a single tube without hairs, which is still able to catch a bubble of air when the insect swims down. We compare both systems from a physical point of view. In the first case it is easier to build a theoretical model and to study theoretically and numerically the shape of the hairs so as to determine the volume of air trapped in the cavity created by the crown of hairs. However, in the second case, it is easier to carry on experiments with a tube and the aim is to determine an empirical law on the volume of air trapped in it. In both cases, it is the variation of the trapped volume of air with the tube radius that is our primary focus.