Authors: F. Varnik and D. Raabe
Affilation: Max-Planck Institut fuer Eisenforschung, Germany
Pages: 647 - 650
Keywords: lattice Boltzmann method, chaotic mixing, flow at rough
Lubricant flows are usually assumed to be laminar and the lubricated<br>metallic surfaces are anticipated to be perfectly flat and references therein). Both assumptions are incorrect<br>when it comes to a detailed analysis. Indeed, metallic surfaces are<br>never flat but reveal an average roughness ranging from some<br>nanometers to some micrometers depending on the mechanical and<br>microstructural boundary conditions. This applies in particular to<br>the evolution of surface roughness during elastic-plastic<br>deformation. This aspect has a strong influence on fluid dynamics at<br>such interfaces. In particular, near-surface fluid flow in the<br>vicinity of a metallic surface may become chaotic and unstable as<br>the surface roughness comes into play. This<br>roughness-induced chaotic flow is not necessarily identical to fully<br>developed turbulence. Nevertheless it exhibits strong<br>temporal and spatial fluctuations of the velocity field.<br> <br>These findings are not only relevant for metal forming, but also<br>for all flow situations where the dimensions of “roughness elements”<br>(obstacles) are about 10% of the channel width or larger. In view<br>of increasing number of potential applications of chaotic flows<br>in civil engineering, environmental industry (e.g.<br>solution recovery) as well as in the medical science (e.g. enhanced<br>chaotic mixing in microchannels), the results of our studies may<br>find a wide range of applications as they open an alternative way<br>for tuning flow properties, namely via a clever design of<br>microchannels.