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1D Euler Boundary Conditions using Riemann Variables??

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Old   December 6, 2010, 14:33
Arrow 1D Euler Boundary Conditions using Riemann Variables??
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Ozan
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Hello all,

I am at the moment writing a code for a uni project using a second order Lax-Wendroff scheme to model unsteady flow.

I am trying to implement boundary conditions using characteristics but am struggling....the method described by Benson for a 'closed' boundary does not produce reflections but results in big oscillations in my program:

1) Do I not need to set the temperature at the boundary to be a constant?

2) Will the homoentropic method at the boundary suffice?

I would really appreciate any help

Thanks,

Ozzy
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Old   December 11, 2010, 16:44
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Alexey
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Quote:
Originally Posted by Ozzy View Post
:

1) Do I not need to set the temperature at the boundary to be a constant?
It depends on flow type at the boundary.

if it's subsonic INflow (M<1) then 2 constant values should be specified, usually total Entalpy and entropy

Entalpy = \frac{\gamma p}{(\gamma-1)\rho}+u^2/2 \

Entropy=\frac{p}{\rho^\gamma}

and 1 parameter should be determined by closest cell inside the domain, ususlly velocity u.

if bounday is subsonic OUTflow then 1 constant parameter
is specified - ambient pressure and 2 others are dtermined by closest cell inside the domain.
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