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DFBI and 6-DOF for Marine Application

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Old   March 31, 2011, 23:02
Default DFBI and 6-DOF for Marine Application
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Naimish Harpal (MS Aerospace Engr)
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Hi all,
I am trying to model a CFD simulation for a sailboat (with rigid type sail) using STAR-CCM+.

As conventional CFD approach (VOF multiphase), I am able to perform Dynamic Fluid Body Interaction (DFBI) simulation for incoming water condition at given speed and wind direction. Note that the boat is kept fixed in water flow-direction.

Now, I want to do the simulation other way around. Target is that the blowing wind (independent of water-direction) should now allow(propel) the boat to move forward in water which is initially set at quiescent condition.

Does anyone has idea about how to setup this problem?

Thanks,
Naimish
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Old   April 1, 2011, 14:44
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So you have used DFBI translation and rotation where the boat is fixed in the mesh? If you want the boat to move in the mesh you can use DFBI morphing.
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Old   April 1, 2011, 15:01
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Naimish Harpal (MS Aerospace Engr)
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Yes, I used 'DFBI Translation & Rotation' approach for simple marine simulation.

Using 'DFBI Morphing' is also a good thought. However, I'm afraid for following: what will happen, with allowed translation in forward direction, when the boat approaches toward the INLET Boundary condition? Will it create any problem? What what be my initial water flow condition?

Another issue with DFBI Morphing is that sometimes solver diverges for large mesh deformation.

Can you put more light on this issue? Really appreciate your comments!
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Old   April 2, 2011, 16:20
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I would only try morphing when everything else fails. Why not stick to DFBI translation and rotation?
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Old   April 7, 2011, 12:54
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Naimish Harpal (MS Aerospace Engr)
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The 'DFBI Translation & Rotation' fails to do so since with allowed freedom in Tx direction, the boat and domain move parallel and thus not influence of relative velocity.

So, only other option is Sliding mesh but will needed larger computational domain OR have to write a UDF at inlet to adjust the balance. What do you think here? Which way is more efficient and accurate at the same time?
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