Eyelashes are ubiquitous, although their function has long remained a mystery. In this study, we elucidate the aerodynamic benefits of eyelashes. Through anatomical measurements, we find that 22 species of mammals possess eyelashes of a length one-third the eye width. Wind tunnel experiments confirm that this optimal eyelash length reduces both deposition of airborne particles and evaporation o...

The complexity of the skewed 3-D boundary layer (figure 3) necessitates the use of multiple coordinate systems. The Tunnel coordinate system is right-handed with the x-axis parallel to the tunnel centerline pointing downstream and the y-axis perpendicular to the tunnel floor pointing up. The Wall-Shear-Stress coordinate system is right-handed with the x-axis in the shear-stress direction at the...

Copyright© 2001 by Gharib, Modarress, Fourguette, and Wilson. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. Abstract This manuscript describes two MEMS based optical sensors for wall shear stress and velocity measurements in flow fields. Experimental results obtained with the wall shear stress sensor, the MicroS3, are compared with boundary layer ve...

Radial x-ray diffraction experiments were conducted under nonhydrostatic compression on SiO2 to 60 GPa in a diamond anvil cell. This ratio of differential stress to shear modulus t/G is 0.019(3)-0.037(5) at P=15-60 GPa. The ratio for octahedrally coordinated stishovite is lower by a factor of about 2 than observed in four-coordinated silicates. Using a theoretical model for the shear modulus, t...

Shear stress driven grain boundary (GB) migration was found to be a ubiquitous phenomenon in small grained polycrystalline materials. Here we show that the GB displacement shift complete (DSC) dislocation mechanism for GB shear coupled migration is still functioning even if the geometry orientation of the GBs deviates a few degrees from the appropriate coincidence site lattice (CSL) GBs. It mea...

We conduct a two-dimensional numerical experiment on the lower crust under an intraplate strike-slip fault based on laboratory-derived power-law rheologies considering the effects of grain size and water. To understand the effects of far-field loading and material properties on the deformation of the lower crust on a geological time scale, we assume steady fault sliding on the fault in the uppe...

[1] Thinning of mantle lithosphere due to Rayleigh-Taylor instability can be a mechanism for triggering continental magmatism near active or recently active plate boundaries. We consider whether it is also plausible as a mechanism for intracontinental magmatism, several hundred kilometers from active subduction or rifting. We perform two-dimensional Rayleigh-Taylor experiments and find that a s...

A thermodynamic model describing the phase transition of first order between structure states of lubricant material in the boundary friction regime is proposed. It is shown that lubricant melts with temperature increase or at shear of rubbing surfaces if the elastic strain (stress) exceeds the critical value. The phase diagram with domains of dry and sliding friction is constructed. The depende...

The main purpose of this paper is to compare the predictions of four laws currently used for the estimation of the wall shear stress in an incompressible turbulent boundary layer-viz., A proposal is also made for a modified skin-friction law which would appear to predict values of the wall shear stress to within about 5 percent over its range of validity. A feature of this new law is that close...

Large volumes of naturally jointed Precambrian crystalline rock can be stably maintained at pressures considerably above the least principal earth stress in the surrounding rock mass. At Los Alamos National Laboratory’s Fenton Hill hot dry rock (HDR) geothermal test site, tests carried out for a cumulative period of 11 months in the deeper and larger of the two HDR reservoirs showed no evidence...