[wanis]

Hello members,
I have tried to compile this UDF but, it seems that there is a problem coding. therefore plz if i can get help to debug it I would appreciate.
Addition info:
I want to change the mass value respect to the time or the value of F_Y as stated in the program, let's say the mass is 100 gram then after certain time will be 90 gram and so on; so if any one here can advice me how? Also if there is any suggestion to re-correct .
Here is my UDF.

The Object is Moving in Three dimensions ( x, y and Z), so the CG will be changed during the motion, so that is why I need to define F_Y depends of CG changes HOW????


# include "udf.h"
# include "dynamesh_tools.h"


DEFINE_SDOF_PROPERTIES(Object_prop, prop, dt, time, dtime)
{
real mass;
real G;
mass = 0.2986;
G = 9.81;
cg = DT_CG(dt)[1];


prop[SDOF_MASS] = mass;
prop[SDOF_IXX] = 0.00178849;
prop[SDOF_IYY] = 0.00179058;
prop[SDOF_IZZ] = 0.00166991;
prop[SDOF_ZERO_TRANS_X] = FALSE; /* boolean, suppress translation in x-direction */
prop[SDOF_ZERO_TRANS_Y] = FALSE; /* boolean, suppress translation in y-direction */
prop[SDOF_ZERO_TRANS_Z] = FALSE; /* boolean, suppress translation in y-direction */

prop[SDOF_IXY] = 0.0; /* -0.00000003;*/
prop[SDOF_IXZ] = 0.0; /* 0.00000000;*/
prop[SDOF_IYZ] = 0.0; /* 0.00000000;*/

/* Change mass value */
{
register real F_Y ;
F_Y = mass * G
{
Prop [SDOF_LOAD_F_Y]=F_Y;
}
if (F_Y < mass*G)
{
prop[SDOF_MASS] = mass - 0.01;
}

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

[wanis]

Hello,

I have no idea about to solve the problem yet, i hope u to help me

[hesam267]

Hi.
can anyone explain simple example of SDOF function Please?
i coudnt solve any problem with this udf because of Dynamic mesh error.
can you clear it with for example one cylindrical (or any other shape) in water bowl?
i think i do something wrong in create dynamic mesh zone.

[alleau]

Hi all,

Wanis : I think your error is coming from :
F_Y = mass * G
{
Prop [SDOF_LOAD_F_Y]=F_Y;
}

which is not correct. Maybe someting like
if(F_Y == mass * G)
{
Prop [SDOF_LOAD_F_Y]=F_Y;
}
should work, but i don't know if it's what you mean.

hesam267, for the explanation of the SDOF solver, it computes fluid external load and momentum on a solid, define as a wall in fluent.
Your error can come from a time discretisation. For example, if your solid is moving faster than your mesh is reform, you might have a negative cell volume.
Hope this help