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May 6, 2014, 11:34 |
Film flow becomes unsteady with more cells
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#1 |
New Member
Join Date: Apr 2014
Location: Germany
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Hello,
I'm simulating a gravity driven film flow over an obstacle with OpenFoam1.6 (Inclination angle 10° and Re between 4 and 30). As a solver a modified version of interFoam is used, so no gravity force acts on the second phase (air). The boundary conditions are cyclic (wave length of the bottom is 2 cm).and the solver settings are taken from the damBreak tutorial, only the Courant Number is decreased to 0,1. For a Mesh consisting of 40000 cells the cases become stationary after about 1 second (see the attached picture) but if i increase the cell number to 160000 the cases are unsteady and something like a standing wave builds up. I do not think that this is physical. Any ideas why increasing the cell number leads to this unsteady behaviour? Kind regards Moritz |
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May 6, 2014, 12:21 |
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#2 | |
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Andrew Somorjai
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Quote:
If you run the (finer mesh) simulation longer does the system come to equilibrium. I'm thinking your simulation might be more accurate and so the total energy of the system dissipates over a longer period of time? |
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May 8, 2014, 08:07 |
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#3 |
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No the simulation with the finer mesh does not come to an equilibrium. For some Reynolds Numbers it seems like the simulation with the finer mesh is close to an equilibrium but then it starts to oscillate.
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May 9, 2014, 16:06 |
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#4 |
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Andrew Somorjai
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May 12, 2014, 05:00 |
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#5 |
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My deltaT is 6*10^-6s and the endTime is 2.5s.
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May 12, 2014, 13:43 |
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#6 |
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Andrew Somorjai
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