Question on the DBFI and morpher options

daveatstyacht · March 7, 2011, 21:55

I was interested in performing a simulation involving a rigid body that is free to translate and rotate attached to an object that will deform. I was wondering is it necessary to use the DFBI morpher option or can I use the DFBI rotation and translation option with the morpher option separately for the part that deforms? If I can avoid morphing the area around the whole rigid object it will save a huge amount of computation, as most of the movement is rigid body motion while just the relative motion of the deforming part requires a deformable mesh.

Regards,
Dave

nickninevah · March 22, 2011, 16:42

I'm trying to do the same thing. Please let me know if you get any useful information on this. I have a set of ships rising up in a water lock. I'm trying to model it with three regions. Bottom stationary. Top region with the ships rising, and I use DFBI Translation and Rotation on them. Middle region is empty water, and it uses the DFBI Morphing to deform.

I have worked out that it needs to be DFBI Morphing for the deformable region. I tried it before with just Morphing on the middle region. Set all my boundaries to Floating. My hope was the the middle region would pick up its motions through the Interface to the top region. No luck. The middle and top regions separated and the simulation crashed.

Now, I'm trying to set it up where the middle region gets its motions from the DFBI Morphing model. And my 6DOF body is defined as the ships which are in the upper region. Problem is, I can't work out how to tell the simulation to use the 6DOF body I defined of the ships. There are no options anywhere in the simulation tree that I can find.

Maybe between the two of us, we can solve each other's problems. Hope this helps some.

nickninevah · March 22, 2011, 18:18

Well, I found out what the problem was. A bug with Star CCM+ 6.02. I tried running a test simulation with DFBI Morpher turned on. Boundary motion was set to use the 6DOF body motions. Ran it in Star CCM+ 5.06, and it worked just fine. Ran again in Star CCM+ 6.02, and I get the same error message I saw before.

So I would recommend you try that setup. Use Star CCM+ 5.06. For the region that shifts as a solid object, apply the DFBI Translation and Rotation model. And the deforming region, use the DFBI Morpher model, with the morphing bodies keyed to 6DOF body motions.

March 7, 2011, 21:55	Question on the DBFI and morpher options	#1
daveatstyacht Senior Member Dave Join Date: Jul 2010 Posts: 100 Rep Power: 16	I was interested in performing a simulation involving a rigid body that is free to translate and rotate attached to an object that will deform. I was wondering is it necessary to use the DFBI morpher option or can I use the DFBI rotation and translation option with the morpher option separately for the part that deforms? If I can avoid morphing the area around the whole rigid object it will save a huge amount of computation, as most of the movement is rigid body motion while just the relative motion of the deforming part requires a deformable mesh. Regards, Dave

March 22, 2011, 16:42	Same problem	#2
nickninevah New Member Nicholas Join Date: May 2009 Location: Seattle, USA Posts: 18 Rep Power: 17	I'm trying to do the same thing. Please let me know if you get any useful information on this. I have a set of ships rising up in a water lock. I'm trying to model it with three regions. Bottom stationary. Top region with the ships rising, and I use DFBI Translation and Rotation on them. Middle region is empty water, and it uses the DFBI Morphing to deform. I have worked out that it needs to be DFBI Morphing for the deformable region. I tried it before with just Morphing on the middle region. Set all my boundaries to Floating. My hope was the the middle region would pick up its motions through the Interface to the top region. No luck. The middle and top regions separated and the simulation crashed. Now, I'm trying to set it up where the middle region gets its motions from the DFBI Morphing model. And my 6DOF body is defined as the ships which are in the upper region. Problem is, I can't work out how to tell the simulation to use the 6DOF body I defined of the ships. There are no options anywhere in the simulation tree that I can find. Maybe between the two of us, we can solve each other's problems. Hope this helps some.

March 22, 2011, 18:18	First Bug Found	#3
nickninevah New Member Nicholas Join Date: May 2009 Location: Seattle, USA Posts: 18 Rep Power: 17	Well, I found out what the problem was. A bug with Star CCM+ 6.02. I tried running a test simulation with DFBI Morpher turned on. Boundary motion was set to use the 6DOF body motions. Ran it in Star CCM+ 5.06, and it worked just fine. Ran again in Star CCM+ 6.02, and I get the same error message I saw before. So I would recommend you try that setup. Use Star CCM+ 5.06. For the region that shifts as a solid object, apply the DFBI Translation and Rotation model. And the deforming region, use the DFBI Morpher model, with the morphing bodies keyed to 6DOF body motions.