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Investigation of temperature-driven flow between ratchet surfaces

Abstract : A novel configuration of Knudsen pump is numerically studied in this paper. The pumping element consists of two facing isothermal ratchet surfaces at different temperatures. Since the main practical difficulty associated with traditional Knudsen pumps which refers to the necessity to accurately control the temperature gradient imposed along the walls of the device, the possibility of independently heating or cooling two distinct surfaces can be considered as a turnaround point in the design simplification of such new generation pumps. The micrometric dimensions of the pump provide the necessary conditions for obtaining rarefied gas inside the device and the asymmetric saw-tooth-like surfaces provide the optimal geometrical conditions in order to create temperature inequalities along the flow that finally engender a macroscopic gas movement. The rarefied flow is numerically investigated by Direct Simulation Monte Carlo (DSMC) in a large range of Knudsen number. The mass flowrate reaches a maximum value for a Knudsen number around 0.1 and becomes negative for a Knudsen number close to unity. A bidirectional flow depending on the Knudsen number value is observed and described. The temperature distributions, flow patterns and generated flow rate are investigated for different Knudsen numbers and also with different accommodation coefficients on vertical and inclined walls of the ratchet surfaces. The results are sensitive to the local boundary conditions.
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https://hal.archives-ouvertes.fr/hal-02051902
Contributor : Pierre Naegelen <>
Submitted on : Thursday, February 28, 2019 - 10:39:57 AM
Last modification on : Thursday, February 27, 2020 - 1:10:32 AM

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  • HAL Id : hal-02051902, version 1

Citation

Jie Chen, Stefan Stefanov, Lucien Baldas, Stéphane Colin, Christine Barrot-Lattes, et al.. Investigation of temperature-driven flow between ratchet surfaces. 2th European Conference on Non-equilibrium Gas Flows (NEGF15), Eindhoven, the Netherlands, 2015, Eindhoven, Netherlands. pp.101-109. ⟨hal-02051902⟩

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