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September 23, 2011, 16:45 |
interface problem
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#1 |
Member
vyc
Join Date: Jul 2011
Posts: 31
Rep Power: 14 |
Hello,
I have problem with mesh inter face: If I do not set Inflation in the moving interface part interface works, but my y+ is terrible more then 1000.... if I set Interface the solver do not solve and stop with error. So my question is how to set interface witch can convergent. Or, if in the part, which is in my solution is only pressure generator, can be very big y+ >1000. Is it will have affect on my interesting zone marked color black? it means for pressure or velocity numbers? Vyc |
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September 24, 2011, 07:33 |
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#2 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,665
Rep Power: 143 |
Sorry, I do not understand your question, and your images are too small to be useful.
Whether y+>1000 is a problem or not depends on your simulation. If the boundary layers do not significantly contribute to the result then this is fine. If boundary layers do significantly contribute then you almost certainly need to improve the near wall mesh. |
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September 28, 2011, 04:48 |
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#3 |
Member
vyc
Join Date: Jul 2011
Posts: 31
Rep Power: 14 |
hello, ghorrocks
thank You for replay I put new figure with my problem I have problem with mesh inter face: If I do not set Inflation in the moving interface part interface works, but my y+ is terrible more then 1000.... if I set Interface, the solver do not solve, and stop with error. So my question is how to set inflation witch can convergent with moving mesh. Or if I leave moving interface parts (red color) with y+ more then 1000, pressure and velocity results will be accurate at the static inter face zone (black color)? Vyc |
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September 28, 2011, 08:21 |
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#4 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,665
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If you are modelling a valve cracking open with a large pressure behind it I think you will find that boundary layer resolution is of secondary importance. In this case your large y+ would not be a problem (but you will probably have to refine the mesh anyway).
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September 28, 2011, 12:30 |
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#5 |
Member
vyc
Join Date: Jul 2011
Posts: 31
Rep Power: 14 |
Hello, ghorrocks,
thank You for replay Yes You are right it is valve opening problem sorry that I do not mentioned. I want to solve it in that way: set pressure and temperature in the cylinder just before opening outlet window. And then it opens I shall get right pressure and velocity numbers. But if I set these parameters as initial in cylinder zone, rapidly vanish before opening outlet window. Question: how set pressure and temperature in cylinder ? |
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September 28, 2011, 21:07 |
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#6 | ||
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,665
Rep Power: 143 |
Quote:
Quote:
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September 30, 2011, 04:24 |
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#7 |
Member
vyc
Join Date: Jul 2011
Posts: 31
Rep Power: 14 |
hello, ghorrocks
thank You for replay I still have problem with pressure set ups in the first picture I set initial pressure in the second picture from results file I can see higher pressure 0,2MPa in the cylinder and 0Pa in muffler but in the third picture after very short time pressure start drop up to 10time lower and in the muffler I got negative pressure ? when intersection still not overlap why? it should stay constant cylinder only move not deforming (cylinder volume constant) I think that initialization should be set some how different thanks for any suggests vyc |
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October 3, 2011, 18:49 |
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#8 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,665
Rep Power: 143 |
You have a problem with your initial conditions and/or boundary conditions.
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