# How can I deal with deformable body in CFX?

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 July 3, 2014, 10:33 How can I deal with deformable body in CFX? #1 Member   Sangwoo Kim Join Date: Jul 2014 Location: Seoul, South Korea Posts: 91 Rep Power: 3 Hi. I'm a new user of CFX. I'm trying to simulate wheels rotating on the road, and it is difficult to handle a deformation of rubber tire. I think it can be solved by assuming that the tire rubber is deformed by specific angle or something and using dynamic mesh in FLUENT. What about in CFX? Actually, I just have a conceptual idea of using dynamic mesh in FLUENT. I don't know how to do, and even whether it is possible or not. Is there a material that would be helpful in this case? Thank you.

 July 3, 2014, 18:41 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 10,931 Rep Power: 85 Why do you need to use deforming mesh? Can't you apply the rotation of the tyre as a tangential wall motion on a fixed mesh?

 July 3, 2014, 20:44 #3 Member   Sangwoo Kim Join Date: Jul 2014 Location: Seoul, South Korea Posts: 91 Rep Power: 3 Thank you for your reply, ghorrocks. Because the part of the tire in contact with the ground is deformed flat. Tire will be treated as keeping rotating, and deformed part will be changed continuously. So I think a fixed mesh is not proper.

 July 3, 2014, 21:36 #4 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 10,931 Rep Power: 85 If you look at the motion in the frame of reference of the vehicle then the surface of the tyre has no normal motion, only tangential. Therefore moving mesh is not required, just a tangential velocity on a stationary mesh. The deforming bit will just mean the tangential velocity is not a pure rotational motion. But I bet assuming it is a pure rotation will be so close as to be good enough.

 July 3, 2014, 21:59 #5 Member   Sangwoo Kim Join Date: Jul 2014 Location: Seoul, South Korea Posts: 91 Rep Power: 3 You mean it is enough to simulate just a circle tangential with a line? Then, if I want more realistic analysis, so deformation of tire should be considered, is stationary mesh still enough?

 July 3, 2014, 22:46 #6 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 10,931 Rep Power: 85 I do not understand your comment "You mean it is enough to simulate just a circle tangential with a line?" Have a think about how a tyre rolls along, and look at it from the frame of reference of the vehicle. Then you will see what I am talking about.

 July 4, 2014, 00:26 #7 Member   Sangwoo Kim Join Date: Jul 2014 Location: Seoul, South Korea Posts: 91 Rep Power: 3 What I asked was whether or not it's fine to ignore the deformation of tire rubber. And I wanted to include deformation whether it is negligible or not. I will try to do, anyway. Thanks very much for your advice

 July 7, 2014, 10:50 #8 Senior Member   Join Date: Apr 2009 Posts: 516 Rep Power: 12 I think you're missing Glenn's point. Generate a mesh that includes the flat-spot on the tire, then apply a wall velocity to the tire surface. This does not move/deform the mesh.

 July 9, 2014, 02:44 #9 Senior Member     Marcin Join Date: May 2014 Location: Poland, Swiebodzin Posts: 120 Rep Power: 3 Dont use CFX for this analysis . Use LS-Dyna for contacts problems. On this module you can define elasto/visco plastic material for rubber, rotational speed, vertical force and contact beetween surface and wheel.

 July 9, 2014, 02:48 #10 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 10,931 Rep Power: 85 I am assuming Sangwoo is looking at the air flows over a tyre. LS-DYNA is not so good for this and CFX is a good choice for this type of analysis. But yes, if the shaped of the deformation of the tyre is the important thing then something like LS-DYNA should be considered.

 July 9, 2014, 03:03 #11 Member   Sangwoo Kim Join Date: Jul 2014 Location: Seoul, South Korea Posts: 91 Rep Power: 3 Oh got it. You are right. Problem was that I didn't understand how moving wall function acts. It was silly question. Thank you very much.

July 9, 2014, 03:06
#12
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Sangwoo Kim
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Quote:
 Originally Posted by Martin_Sz Dont use CFX for this analysis . Use LS-Dyna for contacts problems. On this module you can define elasto/visco plastic material for rubber, rotational speed, vertical force and contact beetween surface and wheel.
Thanks for your reply. But I'm interested in airflow in the wake of the wheel as Glenn says.
My words might be confusing.

July 9, 2014, 03:07
#13
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Sangwoo Kim
Join Date: Jul 2014
Location: Seoul, South Korea
Posts: 91
Rep Power: 3
Quote:
 Originally Posted by ghorrocks I am assuming Sangwoo is looking at the air flows over a tyre. LS-DYNA is not so good for this and CFX is a good choice for this type of analysis. But yes, if the shaped of the deformation of the tyre is the important thing then something like LS-DYNA should be considered.
I finally got it what was wrong.
Really thank you for considerate replies =)

 May 21, 2015, 11:56 please share your findings #14 New Member   PG Join Date: Apr 2015 Posts: 1 Rep Power: 0 Hi, I think I'm trying to model a similar problem. Could you share what you figured out about flow around a tire in contact with gorund surface?

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