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forces.c HELP!!!

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Old   May 1, 2019, 21:37
Exclamation forces.c HELP!!!
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Hi,

Hope you guys are doing well. I posted a similar question some time ago but didn't get any answer and I am still stuck so I thought I might post it again:


I am using forces.c to calculate the moments and lift and drag forces on a turbine airfoil rotating. I have following problems/questions if someone can help me:


1) Are the moments and forces calculated in the global cartesian system ?
2) How is the moment calculated from force ? Is it the normal distance from patch to the center of rotation ? If so, when I am running 2D simulation, why do I get huge values for the x and y moments ? They should be zero or machine tolerance
3) I calculated the z moment and then calculated the moments manually by resolving force components into tangential and radial components and multiplying with constant radius (the radius varies as a function of patch but should be close enough). I get a the total (integrated over rotation) moment from forces twice what I get from the actual moment in z direction calculated by OpenFOAM and the moments calculated from forces is what I would actually expect. Can someone shed some light on this problem ?
4) How exactly do bins work and what do they do ? If I understand correctly, bins spatially partition the patch and get forces and moments in a specific direction. Is that correct or am I totally off ? If this is true how is the spatial partition computed or set ?



I can send whatever supporting or results files you guys need. They are a bit large so I will upload required files on drive and then send them


Thankyou,
h7ris
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force coefficients, forces, moments

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