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June 17, 2018, 01:15 

#21  
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As you have already determined, the position is consistent after restarting Fluent, but what about ? 

June 17, 2018, 01:19 

#22  
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Please don't go out of your way to do this but. If you have some time to kill only then do it cos it will take a day easily. That was very kind of you to offer to simulate it yourself. 

June 17, 2018, 01:20 

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June 17, 2018, 01:24 

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I have not used the Six DOF solver before, and I do not have this version of ANSYS installed to have a quick check. Is there any mention in the Fluent guides? Otherwise have a look around the GUI?


June 17, 2018, 01:30 

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Yea, will do that. I have restarted a simulation for another case to see if this happens in that too. If it does, then next time I will use the UDF approach. But honestly, I would expect the same thing to happen there too cos the UDF will only have the mass, spring constant and 1dof as parameters, not initial equilibrium position.


June 17, 2018, 01:47 

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If you only want a single DOF such that the restoring force of the spring acts purely in the ydirection, then the force on the cylinder could be calculated with: Code:
force = k*(DT_CG(dt)[1]  x_equilibrium[1]); Note: remember that indexing in C starts from zero instead of one, so DT_CG(dt)[1] corresponds to the second spatial coordinate (y for Cartesian). 

June 17, 2018, 01:51 

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June 17, 2018, 03:36 

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June 17, 2018, 03:53 

#29 
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Well, this result is consistent with what we consider the problem to be: that the equilibrium position of the spring is being reset on restarting Fluent. I would expect (or at least hope) that using the UDF would solve this issue, and would also give you greater control and transparency on what you are actually solving.
Yes, a 3D simulation would be much more computationally expensive. Remember to optimise your mesh and you could also start with an initial condition based on your 2D result to help reduce the time it takes for the flow/oscillations to fully develop. 

June 17, 2018, 04:02 

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June 19, 2018, 06:50 

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March 4, 2021, 00:37 

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dynamic mesh, restart problem, viv 
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