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-   -   Body to rotate by action of the air flow (http://www.cfd-online.com/Forums/star-ccm/77201-body-rotate-action-air-flow.html)

rpravata June 16, 2010 08:39

Body to rotate by action of the air flow
 
Hi all, I need your help

How can I do for a body to rotate by action of the air flow?

I want to know the speed of rotation as a function of air velocity.

Do I have to do with "moving reference frame model? or "rigid body motion model?

Many thanks.

f-w June 16, 2010 11:29

What you need to use to accomplish your goal is the "6-DOF Motion Model." You can then setup reports to monitor rotation rate.

Since this is a complicated model, I suggest you read all the help documentation and practice on very simple geometry first.

rpravata June 27, 2010 14:31

THANKS!!!

but one more question
how do I put up resistance to rotation.

thank you very much

f-w June 28, 2010 11:38

HELP > Modeling > Modeling Dynamic Fluid Body Interaction > Working with 6-DOF Bodies > What are External Forces and Moments? > Adding an External Force or Moment

Read the help file, there's a damping moment, and a damping force you can add.

rpravata June 29, 2010 10:19

Yes, thank very much.

You are the Best.

From Spain realy thanks.

rafasdo August 9, 2010 16:31

Hi rpravata,

Do you had success in simulation? Here, I have a channel (2D) with a square in the middle and I'd like to simulate the rotate this object by action of the fluid flow. I've been using a 6DOF udf together with dynamic mesh, but when I run the solver after some iterations appear the following error: Warning: negative volume detected --> repeat smoothing!
I've tried decrease the time step, but the error persists. Following below the udf that I've been using:

include "udf.h"

DEFINE_SDOF_PROPERTIES(quadrado, prop, dt, time, dtime)

{
prop[SDOF_ZERO_TRANS_X] = TRUE;
prop[SDOF_ZERO_TRANS_Y] = TRUE;
prop[SDOF_ZERO_TRANS_Z] = TRUE;
prop[SDOF_ZERO_ROT_X] = TRUE;
prop[SDOF_ZERO_ROT_Y] = TRUE;

/* Define the mass matrix */

prop[SDOF_MASS] = 1;
prop[SDOF_IXX] = 0.25;
prop[SDOF_IYY] = 0.25;
prop[SDOF_IZZ] = 0.50;

printf ("\n2d_test_box: Updated 6DOF properties");
}


Quote:

Originally Posted by rpravata (Post 263242)
Hi all, I need your help

How can I do for a body to rotate by action of the air flow?

I want to know the speed of rotation as a function of air velocity.

Do I have to do with "moving reference frame model? or "rigid body motion model?

Many thanks.



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