Thermally induced gas flows in ratchet channels with diffuse and specular boundaries
| Autor: | Steffen Hardt, Ehsan Roohi, Tobias Baier, Vahid Shahabi |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
Physics
Multidisciplinary Ratchet 02 engineering and technology Mechanics 021001 nanoscience & nanotechnology 01 natural sciences Article 010305 fluids & plasmas Physics::Fluid Dynamics Reflection symmetry Flow (mathematics) 0103 physical sciences Knudsen pump Direct simulation Monte Carlo Specular reflection Boundary value problem Knudsen number 0210 nano-technology |
| Zdroj: | Scientific Reports |
| ISSN: | 2045-2322 |
| Popis: | A net gas flow can be induced in the gap between periodically structured surfaces held at fixed but different temperatures when the reflection symmetry along the channel axis is broken. Such a situation arises when one surface features a ratchet structure and can be augmented by altering the boundary conditions on different parts of this surface, with some regions reflecting specularly and others diffusely. In order to investigate the physical mechanisms inducing the flow in this configuration at various Knudsen numbers and geometric configurations, direct simulation Monte Carlo (DSMC) simulations are employed using transient adaptive subcells for collision partner selection. At large Knudsen numbers the results compare favorably with analytical expressions, while for small Knudsen numbers a qualitative explanation for the flow in the strong temperature inhomogeneity at the tips of the ratchet is provided. A detailed investigation of the performance for various ratchet geometries suggests optimum working conditions for a Knudsen pump based on this mechanism. |
| Databáze: | OpenAIRE |
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