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Old   May 24, 2008, 05:55
Default 6 DOF
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Hi ! I am doing a 2D simulation in Fluent for the motion of a rigid sphere in a fluid column . The simulation is going fine in the dymanic mesh > 6DOF solver. The problem is when the sphere translate down the column,how can we track its CENTER OF GRAVITY with time? In the Dynamic meshing > zone , the CG of the ball updates with each time step. but how can we get its plot with time.

Any help regarding this problem is highly appreciated.

Regards, Lavanjay
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Old   May 27, 2008, 05:59
Default Re: 6 DOF
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HI!!! You can find CG position by using Fluent UDF function. For example you can find cg position and angle of rotation of rigid body by apply the following functions: // XYZ x = DT_CG (dt)[0]; //- x y = DT_CG (dt)[1]; //- y z = DT_CG (dt)[2]; //- z // angles of rotation a = DT_THETA (dt)[0]; b = DT_THETA (dt)[1]; c = DT_THETA (dt)[2]; You can write down obtain values of body position in file. Plots of displacement could be done in TechPlot for instance.

On the other hand you could monitor CG position as a surface monitor of considered rigid body. (I think second approach coud be used while CG is located in the centre of you sphere)

Also I have a lot of questions about 6DOF solver of Fluent.

How can we define CG position of body (ship for example)? What values of inertia tensor we must set up as a parameter of 6DOF in a such case?

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