Thesis

Benchmarking, development and applications of an open source DSMC solver

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Awarding institution
  • University of Strathclyde
Date of award
  • 2013
Thesis identifier
  • T13487
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Abstract
  • Several important engineering gas flow problems fall within the transition Knudsen number regime, e.g. re-entry of spacecraft, or gas flows in micro-scale geometries. The transition regime remains the most difficult to obtain reliable analytical or numerical results for, but the most successful method has been the direct simulation Monte Carlo (DSMC) numerical technique. Due to the nature of high temperature, hypersonic flows, and equipment limitations at the micro-scale, there is a scarcity of reliable experimental data for transition regime flows; numerical experiments using DSMC are an essential tool for the design of engineering systems that encounter these kinds of flows. We benchmark a recently developed open-source DSMC solver against existing DSMC solvers, analytical solutions, and experimental data. The solver is then extended to include some important features that enable it to be applied to a larger range of engineering problems. Vibrational energy and the quantum-kinetic chemical reaction model are implemented in our DSMC solver, preparing it for use with hypersonic flow problems with shockwaves and local regions of very high temperature. Low speed fixed pressure boundary conditions are also implemented, for use with simulations of gas flows in micro-channels. The extended solver is then used to investigate two different engineering problems. Firstly, simulations of gas flows in micro-channels with bends are performed. We find that the inclusion of a sharp ninety degree bend does not lead to significant losses, and can even lead to a small increase in mass flow rate within a limited range of Knudsen number. Adding a second bend is found to increase this mass flow rate enhancement. Finally, we investigate rarefied gas effects on high area-to-mass ratio spacecraft in low Earth orbit, taking inspiration from the Crookes radiometer. We find that the ii non-equilibrium gas effects can be exploited for use as propellant-free inter-spacecraft position control within a swarm, by altering the temperature of one spacecraft relative to another. A small degree of attitude control can be exercised in a similar manner, through non-uniform heating of an individual spacecraft.
Resource Type
DOI
Date Created
  • 2013
Former identifier
  • 991505

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