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June 2, 2011, 19:44 |
C-Grid Boundary Conditions
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#1 |
New Member
Anonymous
Join Date: Jun 2011
Posts: 5
Rep Power: 14 |
I am using a C-grid from here to analyze the NACA 0012 airfoil using Cradle's SC/Tetra. I am having some trouble setting the boundary conditions. What BCs should I use? For what I have already tried, some regions of the grid develop a very high pressure and others have a very low pressure. (This only happens when the angle of attack is non-zero, and in case it matters, I am simulating the angle of attack by varying the inflow direction).
I hope somebody can help me! Thanks in advance. P.S. I'm obviously new to this forum and hope to become more active once my work gets more difficult. |
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June 6, 2011, 22:18 |
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#2 |
New Member
Anonymous
Join Date: Jun 2011
Posts: 5
Rep Power: 14 |
So far, I have tried making the entire circular portion of the C-grid inflow and the rest a static pressure of 0, making the entire grid natural inflow/outflow and beginning with an initial condition which contained the velocity I wanted, and several other variations of the theme.
Could somebody please help me? |
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June 6, 2011, 23:59 |
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#3 |
Senior Member
Martin Hegedus
Join Date: Feb 2011
Posts: 500
Rep Power: 19 |
I'm not familiar with Cradle's SC/Tetra. If the code is compressible, you should use a characteristic (Riemann) boundary condition.
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June 7, 2011, 15:58 |
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#4 |
New Member
Anonymous
Join Date: Jun 2011
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Is the Riemann BC the same as Natural Inflow/Outflow? This is what I believe, based on the small amount of literature that I actually understand.
Also, where should the Riemann BC be applied? I presume I also need in inlet, and where should that be? |
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June 7, 2011, 18:21 |
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#5 |
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Anonymous
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I'm not sure what you mean. My question is basically: "What BCs should I use for this?"
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June 10, 2011, 16:58 |
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#6 | |
Senior Member
Martin Hegedus
Join Date: Feb 2011
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Quote:
http://turbmodels.larc.nasa.gov/naca0012_val.html Not sure what a "Natural" Inflow/Outflow B.C. is. I'm totally guessing that the idea is the same, but meant for an incompressible solver. Is your solution methodology incompressible? |
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June 10, 2011, 17:49 |
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#7 |
New Member
Anonymous
Join Date: Jun 2011
Posts: 5
Rep Power: 14 |
Yes, my simulation is incompressible. Natural inflow outflow is a BC in which the air can freely move out and into the domain.
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