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Numerical and experimental analysis of flows generated by temperature fields in rarefied gas : application to the design of Knudsen micropumps

Abstract : This thesis presents a numerical and experimental analysis of internal rarefied gas flows induced by temperature fields. In rarefied gases, a flow can be generated by solely applying a tangential temperature gradient along a wall: without any initial pressure gradient, the gas macroscopically moves from the cold toward the hot region. This phenomenon is the so-called thermal creep or thermal transpiration effect. It is the main operating principle of the Knudsen pump, which can generate gas pumping without the need of any moving parts. The main aspect of this work is centered on numerical investigations of thermal transpiration flows in three new possible configurations of Knudsen pumps. For that goal, a numerical model for slip flows has been developed in which the appropriate slip boundary conditions are implemented in a commercial CFD code and a DSMC code has been adapted for studying transition flows in complex geometries. The pumping effect of curved-channel Knudsen pumps, the thermal transpiration flows through tapered channels and between two ratchets surfaces at different uniform temperatures have been investigated. In addition, an experimental study of thermal transpiration flow through a single micro-tube has been carried out on a new experimental set-up designed to be adaptable for testing thermally driven flows through various kinds of microchannels or generated by autonomous Knudsen compressors
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  • HAL Id : tel-01511683, version 1

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Jie Chen. Numerical and experimental analysis of flows generated by temperature fields in rarefied gas : application to the design of Knudsen micropumps. Mechanics of the fluids [physics.class-ph]. INSA de Toulouse, 2016. English. ⟨NNT : 2016ISAT0009⟩. ⟨tel-01511683⟩

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