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floating point exception when moving plate comes close to stationary walls |
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June 4, 2017, 06:12 |
floating point exception when moving plate comes close to stationary walls
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#1 |
Member
Michael Frank
Join Date: Aug 2012
Posts: 55
Rep Power: 14 |
Hi,
I running a simulation using interDyMFoam, where a solid plate is free to move within an enclosure. The plate is moving as it should. However, when it comes very close to one of the stationary boundaries, the timestep becomes extremely small ( O(e-20) ) and the simulation eventually stops with a floating point exception. From the stack trace I can see that the problem occurs during surfaceInterpolation::makeDeltaCoeffs() when the dynamic mesh updates ( i.e. dynamicMotionSolverFvMesh::update() ). Does anyone know a way around this issue? Thanks in advance for any help Cheers Mike |
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June 4, 2017, 07:18 |
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#2 |
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Uwe Pilz
Join Date: Feb 2017
Location: Leipzig, Germany
Posts: 744
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It would be valuable if you post your setup here.
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Uwe Pilz -- Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950) |
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June 4, 2017, 08:06 |
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#3 | ||
Member
Michael Frank
Join Date: Aug 2012
Posts: 55
Rep Power: 14 |
Thanks for your reply.
So the case involves an enclosure with a moving plate. There is an inflow and outflow of water which causes the moving plate to move around the enclosure. If it reaches one of the walls of the enclosure it should stop moving. As I mentioned, the system dynamics seem completely fine up to the point where the plate reaches the walls. I assume it has something to do with dynamic mesh dictionary which I now post below. Quote:
The points displacement dictionary is Quote:
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June 15, 2017, 12:16 |
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#4 |
Member
Michael Frank
Join Date: Aug 2012
Posts: 55
Rep Power: 14 |
So I think I figured out what the problem is. As the moving object approaches a wall, the cells between the two solids are becoming continuously smaller. The adjustable timestep decreases continuously to accommodate the fixed CFL, to the point where it results in an error.
Is there a way to stop this behaviour? For example, can I prevent the object from moving past a certain distance away from the wall? Thanks again for any help |
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