How the Sandfish Lizard Filters Particles and What We May Learn from It

Stadler, Anna Theresia; Krieger, Michael

doi:10.1007/978-3-319-95972-6_47

Cited by 1 publication

(3 citation statements)

References 14 publications

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“…Even light and small particles that are not influenced by gravitational settling are likely to settle in this area of the nasal cavity. We previously demonstrated this by carrying out a particle simulation without taking the impact of gravitational acceleration into account (Stadler et al 2018). The described development of the cross-flow velocities did not significantly depend on whether the time-dependent inhalation pattern or the constant velocity of v = 0.8 v max was prescribed at the outlet to the trachea.…”

Section: Flow Simulationmentioning

confidence: 87%

“…We estimated the minimal particle size that could still be filtered by the geometry of the sandfish lizard's nasal cavity. A previous study Stadler et al (2018) shows that both gravitational and inertial forces are relevant in order to trap sand particles on a sticky, mucus-covered surface. Both mechanisms depend on particle size and density; smaller and lighter particles would closely follow the flow streamlines into the trachea.…”

Section: Minimum Particle Size 231 Theoretical Approachmentioning

confidence: 97%

“…The sandfish lizard has a characteristic respiratory pattern that was described in our previous work (Stadler et al 2016, 2018. For simulation, each phase of the ventilation cycle (exhalation, inhalation, relaxation and pause) was integrated and interpolated by quadratic and cubic spline functions in MATLAB (R2016a, MathWorks, USA), and subsequently programmed in C to create a user defined function (UDF), which was compiled and integrated in ANSYS Fluent.…”

Section: Simulation Of the Air Flowmentioning

confidence: 99%

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The sandfish lizard’s aerodynamic filtering system

2020

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Particulate air pollution has an adverse effect on cardiovascular and respiratory health. Air filtration systems are therefore essential in closed indoor environments. While mechanical filtration is described as an efficient technology, particle filters may act as a source of pollution if not correctly installed and frequently maintained. The sandfish lizard, a sand swimmer that spends nearly its whole life in fine desert sand, inspired us to rethink traditional filtering systems due to its unique ability of filtering sand from its nasal cavity. During a slow, prolonged inhalation, strong cross-flow velocities develop in a certain region of the upper respiratory tract; these cross-flows enhance gravitational settling and force inhaled sand grains towards the wall where they adhere to mucus, which covers the walls in this region. During an intense, cough-like exhalation the particles are blasted out. In this work, the sandfish’s aerodynamic filtering system was analyzed experimentally and by computational fluid dynamics simulations to study the flow profile and particle trajectories. Based on these findings, we discuss the development of a biomimetic filtering system, which could have the following advantages: due to the absence of a membrane, total pressure losses can be reduced. The mucus-covered surface would be mimicked by a specifically treated surface to trap particulate matter. Also, the device would contain a self-cleaning mechanism that simulates the lizard’s exhalation. This biomimetic filtering system would therefore have an enhanced life-time and it would be low-maintenance and therefore economical and sustainable.