Trouble to startup a supersonic flow over a triangle

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Jimmy

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Sep 10, 2009, 6:32:57 PM9/10/09
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I've been trying to run simulations that consist of a supersonic
freestream flowing over a triangular obstacle. The problem I'm facing
most of the time is to startup the simulation, especially when the
flow turns around sharp corners. To provide an example, I uploaded a
script called "Wedge", which generates a NaN at the 15th phase. Does
the simulation crash because of a zero or negative pressure? Is there
another scheme that is better suited for this type of problem?

James Quirk

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Sep 10, 2009, 9:15:44 PM9/10/09
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Jimmy,

You're using a linearized Riemann solver that cannot preserve
positive pressures in the strong expansion you get at sharp
corners. The script:

amrcp bcg/axs.3

will generate 108 alternative solvers for the ReactiveEulerEquations.
Most of them will suffer from the same numerical weakness
but those that use the lax-friedrichs flux should prove
more roubust. For example, try using:

plugin amr_sol
ReactiveEulerEquations {
space = two-dimensional
}
BasicCodeGenerator {
scheme = contrib'axs
solver = jimmy
flux = axs/lax-friedrichs
interp = axs/WENO-A
}

and if that doesn't work try using for interp axs/minmod .

James

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