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moment of inertia in dynamicMeshDict

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Old   June 18, 2018, 05:15
Smile moment of inertia in dynamicMeshDict
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Jiadong Wang
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Dear Foamers,
Iím working on the wingMotion tutorial now, and try to input my foil geometry (e.g. NACA0015) and mesh.

Does anyone know how to calculate the moment of inertia of a NACA foil in dynamicMeshDict (namely, momentOfInertia)? Iím wondering is there any tool or functionality in OpenFoam to calculate the moment of inertia of geometry.

I presuming the momentOfInertia (1.958864357 3.920839234 2.057121362) in dynamicMeshDict means (Ixx, Iyy, Izz).
But for a two-dimensional case, the moment of inertia means area or still volume?

Any advice and suggestions are appreciated.
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Old   June 19, 2018, 05:13
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Hi,

I would say still volume, as a 2D case in OpenFOAM is 3D, but with "empty" patches in the out-of-plane direction, where you also have 1 cell in thickness in that direction.

Regards,
Tom
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Old   June 20, 2018, 00:54
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Hi Tom,

I guess you are right. Thank you very much.

So, I should input a moment of inertia for the new geometry based on 3D volume.
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Old   August 18, 2018, 12:09
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Fredi Cenci
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Hello,



Is this the mass moment of inertia? kg.m^2

Or the area moment of inertia ? m^4



Thank you
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Old   August 19, 2018, 20:55
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Quote:
Originally Posted by fredicenci View Post
Hello,



Is this the mass moment of inertia? kg.m^2

Or the area moment of inertia ? m^4



Thank you
I guess it's mass moment of inertia, kg.m^2.
I tested several cases using this and everything is okay.
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Old   August 19, 2018, 21:34
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Thank you.
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Old   March 6, 2021, 15:22
Default half geometry
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Hey,

I am simulating a ship. Due to symmetry I am only working with half of the geometry. for Dynamic mesh I have following doubts

1. centre of mass - the centre of half or full geometry
2. moment of inertia -moment of inertia of half geometry or (moment of inertia of full geometry)/2


Thanks in advance
vava10
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