[jiadongw]

Dear Foamers,
I’m 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)? I’m 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.

[tomf]

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

[jiadongw]

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.

[fredicenci]

Hello,



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

Or the area moment of inertia ? m^4



Thank you

[jiadongw]

Originally Posted by fredicenci

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.

[fredicenci]

Thank you.

[vava10]

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