[leoarmas]

Hello World!

I have been working in the past few days trying to understand UDFs but i think i've reached a dead end...

This is what i'm trying to do:

I'm just trying to simulate the flow around a body wich is moving up and down with a sinusoidal law of motion. To do this i have written my UDF just as is shown below:

#include "udf.h"

DEFINE_CG_MOTION(object_mov, dt, vel, omega, time, dtime)
{
real a, w, pi;

pi = 3.1415;

/* define motion variables */
a = 0.05; /* 0.05m movement amplitude */
w = 2 * pi * 2; /* 2Hz frequency */

/* define object movement law */
vel[0] = 0;
vel[1] = -a * w * sin(w*time);
vel[2] = 0;
}

I have no problem interpreting this UDF into Fluent. However, when defining the dynamic zone the following warning appears:

"Warning: incorrect cg motion UDF wing on zone 4 (assuming no motion)"

Do you have any clue why could this be? is my UDF correctly written?
Looking forward to your answer.
Thanks!

[leoarmas]

Just to say that I have solved the problem: CG motion macro only works when compiled!!

[Jessica.S]

Hi,
your missing a math header, try using these:

#include "udf.h"
#include "stdio.h"
#include "stdlib.h"
#include "math.h"
#include "dynamesh_tools.h"
#include "storage.h"

In addition, define an intermediate (i.e. "real v = 0") variable for the motion:

v = -a * w * sin(w*time);
vel[1] = v;

hopefully it will solve your problem...

[hossein66]

Originally Posted by leoarmas

Just to say that I have solved the problem: CG motion macro only works when compiled!!

How do you fix it? I have this problem but I can't fix it! Can you help me?

[roham4peace]

I cant write udf code for flapping motion in hover, help me, im so confused

[Jessica.S]

do it with solidworks flow simulation.

J

[manahara]

Originally Posted by hossein66

How do you fix it? I have this problem but I can't fix it! Can you help me?

Hi, Define CG Motion can only be compiled not interpreted. Please try compiling the UDF rather

[morteza 1374]

Originally Posted by manahara

Hi, Define CG Motion can only be compiled not interpreted. Please try compiling the UDF rather

hi
I am the student of fluid mechanics and now I am studying on fluid project. The subject of my project is about blade turbine that Oil radially impacts to the turbine blades by a nozzle, causing the turbine to spin. I have a problem in modeling of turbine that I don’t know how to obtain moment of inertia of blade and fluid and how to relate this challenge to the Cg motion until I can model this turbine in fluent software. Please help me
Thank for your attention

[arunraj]

Hi everyone,

I am simulating flapping wing of aerofoil. I have created three zones, zone 1, 2 and 3. Zone 1 has aerofoil with structured mesh around the aerofoil. Zone 2 and 3 has unstructured gird. My problem is I have properly followed all the steps. But I am not able to achieve what I want. Because the shadow of the interface is taking as wall and is not moving along with the domain. Kindly someone help in sorting out this issue. I have attached my UDF alos. Please have a look. Thank you so much

https://drive.google.com/file/d/0B7L...ew?usp=sharing
https://drive.google.com/file/d/0B7L...ew?usp=sharing

[Rubel Ahammed]

Dear Experts,

I am trying to do a moving mesh for a body which is moving up and down. To do this I have written below UDF:

#include "udf.h"

static real velx = 0.0;

DEFINE_CG_MOTION(box,dt,vel,omega,time,dtime)
{
NV_S(vel, =, 0.0);
NV_S(omega, =, 0.0);

velx = 0.05 * sin(3.1415927 * time / 10.);
Message ("time = %f, vel[0] =%f\n", time, vel[0]);
}

during compile i have face below error mentioned below:


Error: The UDF library you are trying to load (D:\MR Damper\CG Motion\Moving Mesh_files\dp0\FFF\Fluent\libudf) is not compiled for 2d on the current platform (win64).

The system cannot find the file specified.

D:\MR Damper\CG Motion\Moving Mesh_files\dp0\FFF\Fluent\D:\MR Damper\CG Motion\Moving Mesh_files\dp0\FFF\Fluent\libudf\win64\2d\libudf.d ll


How can I solve this problem? looking forward to your answer.
Thanks

[Jessica.S]

Honestly, if you can do it in star ccm+

Ansys suck where moving geometries and large displacements are needed...

[AlexanderZ]

Originally Posted by Rubel Ahammed

Dear Experts,

I am trying to do a moving mesh for a body which is moving up and down. To do this I have written below UDF:

#include "udf.h"

static real velx = 0.0;

DEFINE_CG_MOTION(box,dt,vel,omega,time,dtime)
{
NV_S(vel, =, 0.0);
NV_S(omega, =, 0.0);

velx = 0.05 * sin(3.1415927 * time / 10.);
Message ("time = %f, vel[0] =%f\n", time, vel[0]);
}

during compile i have face below error mentioned below:


Error: The UDF library you are trying to load (D:\MR Damper\CG Motion\Moving Mesh_files\dp0\FFF\Fluent\libudf) is not compiled for 2d on the current platform (win64).

The system cannot find the file specified.

D:\MR Damper\CG Motion\Moving Mesh_files\dp0\FFF\Fluent\D:\MR Damper\CG Motion\Moving Mesh_files\dp0\FFF\Fluent\libudf\win64\2d\libudf.d ll


How can I solve this problem? looking forward to your answer.
Thanks

push BUILD button to compile, not load

best regards

[Minato786]

train.c

tunnel.c

error1.PNG

Hello everyone, I'm trying to get my train to move but no matter what I try, I'm not able to compile the files. I'm not sure if its the file having issues or my settings are the problem. I hope someone could shed some light on this for me.

Thanks

[AlexanderZ]

Originally Posted by Minato786

Attachment 73214

Attachment 73215

Attachment 73216

Hello everyone, I'm trying to get my train to move but no matter what I try, I'm not able to compile the files. I'm not sure if its the file having issues or my settings are the problem. I hope someone could shed some light on this for me.

Thanks

read error log

[Gyansetu]

The program is wrong, even I have also stuck with the same problem.

[Furkanenes76]

I also get the same warning with you. However, when I try to compile my UDF, it is said that libudf does not exist. Did you get any error something like this?

[AlexanderZ]

unload all UDF folders via udf manager,
make any changes in source file you are going to compile
compile

[Furkanenes76]

May you help me with my second question in this forum? I am new in this forum and try to get help. I think there are not enough people seeing my post. I don't know why.

Thank you so much