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stream function & vorticity boundary condition |
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December 4, 2011, 12:45 |
stream function & vorticity boundary condition
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#1 |
New Member
sara
Join Date: Mar 2011
Posts: 7
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HI everyone.
I've wrote a code to simulate velocity field over a square cylinder. I've used vorticity-stream function solver at 0 angle of attack.(not immersed) but now I don't know how to specify outflow boundary condition for different angles of attack. I used a rectangular as my domain. please help me. thank you for reading my thread. |
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December 5, 2011, 10:10 |
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#2 |
Senior Member
Andrew
Join Date: Mar 2009
Location: Washington, DC
Posts: 211
Rep Power: 18 |
I did this for a finite difference method (except I did flow over a step). My exit boundary condition was @x=L, Streamfunction(@x=L) = Streamfunction(@x=L-1). I did this based on assuming that the flow after the step was fully developed and not changing. My vorticity BC was the same. The results were good.
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December 6, 2011, 11:53 |
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#3 | |
New Member
sara
Join Date: Mar 2011
Posts: 7
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Quote:
but in my case I have vortex shedding which makes it more complicated. By the way, did free stream velocity have an angle of attack in your case? or it was simply horizontal? |
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December 6, 2011, 12:08 |
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#4 |
Senior Member
Andrew
Join Date: Mar 2009
Location: Washington, DC
Posts: 211
Rep Power: 18 |
it had no angle of attack, but why can't you extend the rectangular grid long enough to where the vortex shedding has dissipated and the flow is fully developed?
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December 7, 2011, 18:42 |
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#5 | |
New Member
sara
Join Date: Mar 2011
Posts: 7
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Quote:
Well, I did so. but still there are lot's of problems. for example, even if the flow behind the cylinder is fully developed, it still has its angle of attack, so I can't impose the boundary condition you used for outflow. there are other difficulties in dealing with far field boundaries. thank you for your reply. |
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