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Modeling shaking motion Vs Rotational motion

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Old   July 17, 2007, 15:02
Default Dear OpenFoam users While s
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Dear OpenFoam users

While searching for the rotational motion of single frame I have found enough support and explanation. For the rotation one adds terms corresponding to the Coriolis force and the Centripetal Force

volVectorField Fcent = (Omega ^ (Omega ^ mesh.C()));

tmp<fvvectormatrix> UEqn
(
fvm::div(phi, U)
+ turbulence->divR(U)
+ (2*Omega ^ U)
+ Fcent
);
------------------------------------------
In the above case, all the cell centres follow a circular trajectory.

My question is regarding the shaking motion. The object is placed on a platform which shakes with a given frequency and amplitude. I have attached a sketch for clarity. As can be seen from the sketch , a point on the circumference of the object doesn't follows a circular trajectory.
I guess the term:

volVectorField Fcent = (Omega ^ (Omega ^ mesh.C()));

has to be changed as messh.C() varies and depends on the angle of rotation.
Does any body have a clue how the Fcent has to be modified to properly model such kind of behaviour.

With best Regards
Jaswinder


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Old   July 19, 2007, 10:23
Default Hi, Jaswinder, Yes, I looke
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Pei-Ying Hsieh
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Hi, Jaswinder,

Yes, I looked into this type of motion before. Basically, you have to decompose force in X-direction and in Y-Direction (assuming a 2D case in X-Y). Based on omega, you should know the position of the object, i.e., (x, y) as a function of time. Then, do two derivatives to computation acceleration, then, multipy by mass to get Force as function of time.

Pei
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Old   July 19, 2007, 22:44
Default Thanks Pei Shall give it a
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Thanks Pei

Shall give it a try.

Regards
Jaswinder
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