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SOS: the nonpositive k and epsion ,how to get the correct boundary settings |
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March 6, 2012, 00:36 |
SOS: the nonpositive k and epsion ,how to get the correct boundary settings
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#1 |
New Member
zdong
Join Date: Aug 2011
Posts: 15
Rep Power: 14 |
hello everybody,when i try to simulation the pantograph wind tunnel experiment,i got an divergent k and epsilon using simpleFoam or pimpleFoam with k-e turbulent modle.
i have looked though the forum a long time for a solution to this kind of divergent probelm, after changing some related settings follow the tips i got, like checking the model length dimension ,setting the proper magnitude of k and e whenever in the internal field or boundary,setting the relax factor or tolerence for u and p,changing the numerical scheme for k and e , even modifying the solver for k and e, however ,all of this didn't change anything the keypoint should be in the boundary settings,because when i turned off the turbulent modeling, the procedure can run smoothly. those in the attachment is my cas directory , the grid is not in the constant/polyMesh but the boundary dictionary for the file size consideration. anyone could help me out? best regards for you,thanks . abbott |
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March 6, 2012, 02:00 |
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#2 |
Senior Member
Bernhard
Join Date: Sep 2009
Location: Delft
Posts: 790
Rep Power: 21 |
I cannot run your case without the mesh, so it is difficult to spot the error. Can you give the log file? Does it diverge in the first time-step, or only later on? Is your mesh ok (check with checkMesh)?
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March 7, 2012, 21:53 |
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#3 | |
New Member
zdong
Join Date: Aug 2011
Posts: 15
Rep Power: 14 |
Quote:
the log file is in the attachments ,maybe you can find some hints from that .appreciate for your help |
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March 10, 2012, 09:11 |
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#4 |
New Member
zdong
Join Date: Aug 2011
Posts: 15
Rep Power: 14 |
come on ....
i need you help . Even when i chang to the rhoSimplecFoam solver,the problem arise the same,and this time ,the "floating points excepting " error came out at the first iterate when solving the pressure eqution,while the simpleFoam or pimpleFoam prompt the bounding turbulent energy and e at the first iterate ,and then the "floating points excepting " error after several iterate. i will to be crazy ,foamers ,please help me out, thanks so much |
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March 12, 2012, 02:28 |
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#5 | |
Senior Member
Roman Thiele
Join Date: Aug 2009
Location: Eindhoven, NL
Posts: 374
Rep Power: 20 |
Quote:
Hej, first of all calm down, you cannot expect people to answer within minutes. this is a forum of volunteers not your microsoft helpdesk hotline. Second, please check your epsilon and k values, inlet and initial. they seem very high. I don't know what you are simulating, but your values are very large. check the tutorial for values that are more appropriate. k = 0.01 and epsilon = 0.5 and then start varying those values towards what ever you expect to have for your k and epsilon values. try to run the simulation with "standard" values first, as for example the values that are used in the tutorials
__________________
~roman |
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March 12, 2012, 22:49 |
thank for you advice
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#6 | |
New Member
zdong
Join Date: Aug 2011
Posts: 15
Rep Power: 14 |
Quote:
thanks for your advice ,i will follow your suggest. i'a really a lit impatient, however, i will calm myself down and study the tutorials mor carefully.thanks . |
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