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October 16, 2014, 11:43 |
Question about boundary conditions
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#1 |
New Member
Rich
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Can some one explain the riemann invariants in relation to the boundary condition and the isentropic relations.
Last edited by cfdnoob; October 17, 2014 at 15:36. |
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October 16, 2014, 12:16 |
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#2 | |
Senior Member
Filippo Maria Denaro
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Quote:
Any book on compressible flow can help you |
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October 16, 2014, 14:30 |
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#3 |
New Member
Rich
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Do you mean that for pressure, temperature and density you get a machnumber and the other way around?
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October 16, 2014, 14:43 |
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#4 |
Senior Member
Filippo Maria Denaro
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Consider the case of 1D Euler (mass, momentum, energy) equations.
You have 3 eigenvalues u-a, u, u+a, therefore if u<a the first characteristic curve dx/dt=u-a produces an information coming from inner to inflow, as well as produces an information coming from outflow to inner. In case u>a you have a different framework, no information from inner to inflow and no information from outflow to the inner. |
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October 16, 2014, 14:45 |
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#5 |
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Filippo Maria Denaro
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of course a = sqrt(gamma*R*T) = sqrt(gamma*p/rho)
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October 16, 2014, 18:04 |
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#6 |
New Member
Rich
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that sounds like the riemann invariants
In The programm i use it says i need to set 2 (total pressure and temperature) and M is allowed to float. So why are there only 2 things 'coming in' Last edited by cfdnoob; October 17, 2014 at 16:06. |
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