The aim of the current work is to investigate the stability of supersonic and subsonic triple deck flows and liquid layer and jet double deck flows. In particular we aim to investigate the stability properties of the separated flows when coming into contact with a concave or convex corner. The work presented uses two distinct approaches to investigate the stability of the flow. First, a global linear stability analysis, taking disturbances proportional to eAt, is performed. Secondly, numerical simulations have been carried out with the linearised unsteady equations, linearised about a steady state, using forced disturbances. The governing equations are solved in primitive variables format using two different discretization methods. The first method uses finite differences in the streamwise direction and Chebyshev collocation in the wall normal direction and the second method uses finite differences in both spatial directions. The numerical results obtained show good agreement for the global stability analysis and the bifurcation results, with the global stability analysis predicting the bifurcations and indicating the loss of stability at such parameters. Though, in reasonably separated flow, the temporal simulation results disagree with the global stability behaviour. The temporal simulations indicate that the separated flows are unstable with respect to some non-modal instability and that round-off error alone is sufficient enough to trigger this instability.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:488782 |
| Date | January 2008 |
| Creators | Logue, Robert Paul |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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