CG Motion UDF Problem

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 May 18, 2012, 11:30 CG Motion UDF Problem #1 New Member   Leonardo Armas Join Date: Apr 2012 Posts: 2 Rep Power: 0 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!

 June 1, 2012, 11:42 #2 New Member   Leonardo Armas Join Date: Apr 2012 Posts: 2 Rep Power: 0 Just to say that I have solved the problem: CG motion macro only works when compiled!!

 June 2, 2012, 01:21 #3 New Member   Jessica Simberg Join Date: Mar 2012 Posts: 18 Rep Power: 13 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... leoarmas likes this.

August 1, 2012, 06:58
#4
New Member

Hossein
Join Date: Jul 2012
Posts: 2
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Quote:
 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?

 April 10, 2015, 02:59 udf for flapping motion in hover #5 New Member   roham lavimi Join Date: Apr 2015 Posts: 1 Rep Power: 0 I cant write udf code for flapping motion in hover, help me, im so confused

 April 10, 2015, 03:22 #6 New Member   Jessica Simberg Join Date: Mar 2012 Posts: 18 Rep Power: 13 do it with solidworks flow simulation. J

October 9, 2015, 01:55
#7
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Manahara Manatunga
Join Date: Mar 2014
Posts: 15
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Quote:
 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

April 4, 2016, 02:13
#8
New Member

mortezasekaloo
Join Date: Apr 2016
Posts: 4
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Quote:
 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

May 14, 2016, 03:04
Dynamic mesh flapping wing - Interface problem
#9
Senior Member

Arun raj.S
Join Date: Jul 2011
Posts: 190
Rep Power: 13
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

Attached Files
 second.c (1.1 KB, 168 views)

 June 15, 2019, 07:49 CG_Motion udf problem #10 New Member   Rubel Ahammed Join Date: May 2019 Posts: 13 Rep Power: 5 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

 June 16, 2019, 04:31 #11 New Member   Jessica Simberg Join Date: Mar 2012 Posts: 18 Rep Power: 13 Honestly, if you can do it in star ccm+ Ansys suck where moving geometries and large displacements are needed...

June 17, 2019, 02:32
#12
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Alexander
Join Date: Apr 2013
Posts: 2,256
Rep Power: 32
Quote:
 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

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 November 9, 2019, 02:53 I have an issue running my UDF #13 New Member   Sharif Join Date: Nov 2019 Posts: 2 Rep Power: 0 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

November 10, 2019, 23:11
#14
Senior Member

Alexander
Join Date: Apr 2013
Posts: 2,256
Rep Power: 32
Quote:
 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
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 December 20, 2019, 12:59 #15 New Member   Gyan Join Date: Dec 2019 Posts: 1 Rep Power: 0 The program is wrong, even I have also stuck with the same problem.

 March 15, 2022, 02:46 #16 New Member   Furkan Enes Join Date: May 2021 Posts: 3 Rep Power: 3 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?

 March 15, 2022, 06:59 #17 Senior Member   Alexander Join Date: Apr 2013 Posts: 2,256 Rep Power: 32 unload all UDF folders via udf manager, make any changes in source file you are going to compile compile __________________ best regards ****************************** press LIKE if this message was helpful

 February 14, 2023, 08:59 #18 New Member   Furkan Enes Join Date: May 2021 Posts: 3 Rep Power: 3 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

 Tags udf cg motion