干旱区生态环境知识资源中心

The sandfish lizard Scincus scincus spends its life in the aeolian dune deserts. To prevent sand grains from entering its lungs, it is hypothesized that the particles are aerodynamically filtered when they enter the nasal cavity: The vestibulum is a narrow rounded channel leading to a kind of "chamber", where cilia and mucus are present. In this chamber the particles get caught by mucus during a slow, long-lasting inhalation (2s) due to the air flow induced by the characteristic morphology in this area, and eventually get exhaled because of an intense, cough-like exhalation that lasts only 40 ms. To verify this theory we studied the filtering system by integrating experiments and computational fluid dynamic simulations of fluid and particle flow. The simulations show that the flow profile anterior to and in the chamber is characterized by a strong cross-flow velocity that moves the sand grains towards the mucus-covered wall; particles usually remain close to the lower wall of the vestibulum and subsequently get trapped. Due to the air flow profile particles would get trapped even if they reached the central region of the nasal cavity. In this context we explore the possibility to optimize state of the art filtering systems.