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May 23, 2020, 18:52 |
Supersonic Outlet BC
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#1 |
New Member
Join Date: Aug 2019
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Hello, I would like to know how the supersonic outlet boundary condition works on SU2?
Physically it's not necessary a boundary condition (BC) on supersonic outlet, since the flow properties just depends on the upstream properties, but numerically it's necessary some BC. Usually it's extrapolated, using a zero gradient (∇⋅u = 0) or just ∂u/∂x = 0. I took a look at the function BC_Supersonic_Outlet (file CEulerSolver.cpp) and there is a comment saying that the flow variables are interpolated (probably meaning extrapolation). There is also a few lines like this: V_outlet[0] = V_domain[0]; So, is it right to say that what SU2 does is define the flow properties in the outlet as the same value as the upstream? Thanks in advance! Last edited by DGIorio; May 23, 2020 at 23:21. |
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May 23, 2020, 19:46 |
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#2 |
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Pedro Gomes
Join Date: Dec 2017
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That is correct, the supersonic outlet consists of just evaluating the convective flux (as done for the interior of the domain) since there are no incoming characteristics.
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May 23, 2020, 23:21 |
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#3 | |
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Quote:
Just to clarify, it means that it is used ∇⋅F=0 instead of just ∇⋅U=0, where F is the convective flux and U={ρ,ρv,ρE} (using SU2 notation presented in governing equations page). |
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May 24, 2020, 10:30 |
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#4 |
Senior Member
Pedro Gomes
Join Date: Dec 2017
Posts: 466
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What is extrapolated are the primitive variables (not multiplied by density).
In the absence of source terms (spacial or temporal) the divergence of the flux is zero at every node. |
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boundary, su2, supersonic |
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