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2 degree of freedom in one direction UDF

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Old   March 3, 2014, 11:24
Default 2 degree of freedom in one direction UDF
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Linh Tuan The Nguyen
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Hi,

I am doing simulation for flow around free oscillating cylinder. The cylinder was attach with the mass by spring which can be consider as 2 DOF system in one direction (y direction) not 1DOF for each (x, y direction).

I using SDOF in Fluent for single degree of freedom case and it was working fine. But when it's come to 2 DOF, I have no idea how to start.

I am very grateful if anybody can give me some suggestion how to start.

Best Regards
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Old   March 5, 2014, 06:53
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Daniele
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You can use the 6dof solver and create an udf with body properties and use the following lines to have restricted motion:

Transational motion in x direction is not allowed:
Code:
prop[SDOF_ZERO_TRANS_X] = TRUE;
Transational motion in x direction is allowed:
Code:
prop[SDOF_ZERO_TRANS_X] = FALSE;
Transational motion in y direction is not allowed:
Code:
prop[SDOF_ZERO_TRANS_Y] = TRUE;
Transational motion in y direction is allowed:
Code:
prop[SDOF_ZERO_TRANS_Y] = FALSE;
Transational motion in z direction is not allowed:
Code:
prop[SDOF_ZERO_TRANS_Z] = TRUE;
Transational motion in z direction is allowed:
Code:
prop[SDOF_ZERO_TRANS_Z] = FALSE;
Rotational motion around x axis is not allowed:
Code:
prop[SDOF_ZERO_ROT_X] = TRUE;
Rotational motion around x axis is allowed:
Code:
prop[SDOF_ZERO_ROT_X] = FALSE;
Rotational motion around y axis is not allowed:
Code:
prop[SDOF_ZERO_ROT_Y] = TRUE;
Rotational motion around y axis is allowed:
Code:
prop[SDOF_ZERO_ROT_Y] = FALSE;
Rotational motion around z axis is not allowed:
Code:
prop[SDOF_ZERO_ROT_Z] = TRUE;
Rotational motion around z axis is allowed:
Code:
prop[SDOF_ZERO_ROT_Z] = FALSE;
Daniele
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Old   March 7, 2014, 06:50
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Linh Tuan The Nguyen
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Thank Daniele,

I have used this SDOF Macro already for Single degree of cylinder system I have done before and I quite familiar with SDOF Macro. But now I am doing 2DOF in 1 direction, that, the cylinder in the flow domain will be attached with a Mass (see attachment). Do you think in Fluent they have a Macro for this or I have to write my own UDF for this case.


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