[acasas]

I did perform the 2D drop box example in a 3D fashion. It took a lot of resources and time as expected. Now I´m willing to do the same but just over a 1/4 of it applying symmetry in order to reduce resources and run time. In fluent help says: If your moving object consists of a half model, then the symmetry plane has to be specified by providing the components of the normal vector, properties[SDOF_SYMMETRY_X],properties[SDOF_SYMMETRY_Y], and properties[SDOF_SYMMETRY_Z].
I don´t exactly know how to define this . Imagine my symmetry planes are the xy and zy , so the normal vectors are the 0,0,1 and the 1,0,0 . Should my UDF look like this? Please help

#include "udf.h"

DEFINE_SDOF_PROPERTIES(test_box, prop, dt, time, dtime)
{
prop[SDOF_MASS] = 666.66;
prop[SDOF_IXX] = 129.6296;
prop[SDOF_IYY] = 111.1111;
prop[SDOF_IZZ] = 129.6296;
prop[SDOF_SYMMETRY_X] = 1,0,0;
prop[SDOF_SYMMETRY_Z] = 0,0,1;

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

}


Or like this:


#include "udf.h"

DEFINE_SDOF_PROPERTIES(test_box, prop, dt, time, dtime)
{
prop[SDOF_MASS] = 666.66;
prop[SDOF_IXX] = 129.6296;
prop[SDOF_IYY] = 111.1111;
prop[SDOF_IZZ] = 129.6296;
prop[SDOF_SYMMETRY_X] = TRUE;
prop[SDOF_SYMMETRY_Z] = TRUE;

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

}

[macfly]

Hi,

Sorry, I have no idea, I never worked with this kind of udf. I would suggest to implement a very basic case, experiment with SDOF_SYMMETRY_X-Y-Z, and check if you obtain the expected results.

François

[Sixkillers]

Hi,

I have never used 6DOF model, but according to above quote from documentation, which you have posted, you can have only 1 symmetry plane (i.e. 1/2 model).

Symmetry plane is defined by a normal vector. For example I would to have symmetry plane YZ, so normal vector is (1, 0, 0). In UDF it is:

prop[SDOF_SYMMETRY_X] = 1;
prop[SDOF_SYMMETRY_X] = 0;
prop[SDOF_SYMMETRY_X] = 0;

Cheers

[vasava]

I havent done this type of example so I can not give you the right answer. However from the comment in red I understood that you have to input a vector. So something like the following could work.

prop[SDOF_SYMMETRY_X] = [1 0 0];

Or

prop[SDOF_SYMMETRY_X] = (1 0 0);

[acasas]

Originally Posted by Sixkillers

Hi,

I have never used 6DOF model, but according to above quote from documentation, which you have posted, you can have only 1 symmetry plane (i.e. 1/2 model).

Symmetry plane is defined by a normal vector. For example I would to have symmetry plane YZ, so normal vector is (1, 0, 0). In UDF it is:

prop[SDOF_SYMMETRY_X] = 1;
prop[SDOF_SYMMETRY_X] = 0;
prop[SDOF_SYMMETRY_X] = 0;

Cheers

Thank´s sixkillers, you gave me the right information, but I do believe there is a mistake when you did ctrl+c and ctrl+v.... you forgot to change the X...I believe it should be like:

prop[SDOF_SYMMETRY_X] = 1;
prop[SDOF_SYMMETRY_Y] = 0;
prop[SDOF_SYMMETRY_Z] = 0;

thank´s a lot!

[acasas]

Originally Posted by vasava

I havent done this type of example so I can not give you the right answer. However from the comment in red I understood that you have to input a vector. So something like the following could work.

prop[SDOF_SYMMETRY_X] = [1 0 0];

Or

prop[SDOF_SYMMETRY_X] = (1 0 0);

If I use the symmetry, the mass and the moments of inertia must be for the full body , isn´t it? I believe I read it somewhere but I´m not sure. Please correct me if I´m wrong.

Thank´s a lot!!!

[acasas]

Originally Posted by acasas

If I use the symmetry, the mass and the moments of inertia must be for the full body , isn´t it? I believe I read it somewhere but I´m not sure. Please correct me if I´m wrong.

Thank´s a lot!!!

Sorry guys for this last question.... the answer to my own question is yes, in case of a symmetry plane use, the mass and the moments of inertia must be for the full body. The red text below is from the fluent documentation

2.6.5. DEFINE_SDOF_PROPERTIES

2.6.5.1. Description

You can use DEFINE_SDOF_PROPERTIES to specify custom properties of moving objects for the six-degrees of freedom (SDOF) solver in ANSYS FLUENT. These include mass, moment and products of inertia, and external forces and moment properties. The properties of an object which can consist of multiple zones can change in time, if desired. External load forces and moments can either be specified as global coordinates or body coordinates. In addition, you can specify custom transformation matrices using DEFINE_SDOF_PROPERTIES.

Note that if the moving object is modeled as a half model and includes a plane of symmetry, then you have to specify this by providing the normal vector to the symmetry plane. Further, all SDOF properties such as mass and moments of inertia have to be specified for the full body if a symmetry plane is specified.

[acasas]

Guys, just for any one interested on the body symmetry UDF, I did test half of a 3D box similar to the 2D box example available on internet, and I did get same pressure results and same tensions for a 1 way FSI.

if symmetry for the YZ plane then, use:

prop[SDOF_SYMMETRY_X] = 1;
prop[SDOF_SYMMETRY_Y] = 0;
prop[SDOF_SYMMETRY_Z] = 0;

[Far]

excellent work

[Megan]

Originally Posted by acasas

I did perform the 2D drop box example in a 3D fashion. It took a lot of resources and time as expected. Now I´m willing to do the same but just over a 1/4 of it applying symmetry in order to reduce resources and run time. In fluent help says: If your moving object consists of a half model, then the symmetry plane has to be specified by providing the components of the normal vector, properties[SDOF_SYMMETRY_X],properties[SDOF_SYMMETRY_Y], and properties[SDOF_SYMMETRY_Z].
I don´t exactly know how to define this . Imagine my symmetry planes are the xy and zy , so the normal vectors are the 0,0,1 and the 1,0,0 . Should my UDF look like this? Please help

#include "udf.h"

DEFINE_SDOF_PROPERTIES(test_box, prop, dt, time, dtime)
{
prop[SDOF_MASS] = 666.66;
prop[SDOF_IXX] = 129.6296;
prop[SDOF_IYY] = 111.1111;
prop[SDOF_IZZ] = 129.6296;
prop[SDOF_SYMMETRY_X] = 1,0,0;
prop[SDOF_SYMMETRY_Z] = 0,0,1;

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

}


Or like this:


#include "udf.h"

DEFINE_SDOF_PROPERTIES(test_box, prop, dt, time, dtime)
{
prop[SDOF_MASS] = 666.66;
prop[SDOF_IXX] = 129.6296;
prop[SDOF_IYY] = 111.1111;
prop[SDOF_IZZ] = 129.6296;
prop[SDOF_SYMMETRY_X] = TRUE;
prop[SDOF_SYMMETRY_Z] = TRUE;

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

}

Thanks for everyone's solutions. Would you please inform me that in a 6 dof wave-structure interaction, should I preserve the tool bodies in Boolean operation or not?
I think i have a similiar project