CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Fluent UDF and Scheme Programming

incorrect cg motion UDF sdof_properties

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   March 25, 2013, 20:50
Default incorrect cg motion UDF sdof_properties
  #1
New Member
 
Mohamed Magdy Mohamed
Join Date: Jan 2013
Posts: 9
Rep Power: 4
M.Magdy is on a distinguished road
Hi,
I'm trying to simulate the movement of floating body in sea.
I'm using a udf for wall movement :
#include "udf.h"
DEFINE_CG_MOTION(wave, dt, cg_vel, cg_omega, time, dtime)
{
cg_vel[0] = ((4)*(sin((63)*(time))));
cg_vel[1] = 0.0;
cg_vel[2] = 0.0;

cg_omega[0] = 0.0;
cg_omega[1] = 0.0;
cg_omega[2] = 0.0;

}


and another one for the floating body six_dof_property:

/************************************************** *****
SDOF property compiled UDF with external forces/moments
************************************************** *****/
#include "udf.h"

DEFINE_SDOF_PROPERTIES(sdof_properties, prop, dt, time, dtime)
{
prop[SDOF_MASS] = 85167.33;
prop[SDOF_IXX] = 174112.84;
prop[SDOF_IYY] = 28237716.54;
prop[SDOF_IZZ] = 28237716.54;

prop[SDOF_ZERO_TRANS_X] = TRUE;
prop[SDOF_ZERO_TRANS_Y] = TRUE;
prop[SDOF_ZERO_ROT_Z] = TRUE;
printf ("\n updated 6DOF properties");
}

when i check the "six DOF" option in dynamic mesh the wall doesn't move and this message appears:
Unable to read motion history

while if i unchecked it an error appears -
but the waves are generated correctly-:
incorrect cg motion UDF sdof_properties::libudf on zone 6 (assuming no motion)

So if anyone could tell me whether I should -in my case- check the box beside "six DOF" in dynamic mesh options or not.
knowing that :
  • when i check it -----------> no waves are generated (the wall doesn't move)
  • when i uncheck it ---------> waves are generated but the floating body make no motion

Thanks.
M.Magdy is offline   Reply With Quote

Old   March 26, 2013, 03:02
Default
  #2
Senior Member
 
Paritosh Vasava
Join Date: Oct 2012
Location: Lappeenranta, Finland
Posts: 545
Rep Power: 12
vasava will become famous soon enough
Hello Again

I think that you must have something else in your UDF that describes the motion/position of other faces/boundaries in your domain. While you have moving/dynamic face/boundary the motion of mesh attached to this face affects the meshes attached to other faces/boundaries.

I suggest you have a close look at the tutorial titled 'Using a UDF to Control the Dynamic Mesh of a Flexible Oscillating Membrane'.
vasava is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
UDF for 2d translational motion ThinkQuick Fluent UDF and Scheme Programming 5 April 9, 2015 17:46
UDF to control motion NOT about CG LenDawg0220 Fluent UDF and Scheme Programming 0 July 28, 2012 12:54
UDF for butterfly valve motion, need help g-wagon Fluent UDF and Scheme Programming 0 November 21, 2011 01:55
UDF for Airfoil in Circular motion (2D) sohail_27 Fluent UDF and Scheme Programming 4 October 4, 2010 13:36
UDF error CG Motion Alex FLUENT 0 March 22, 2006 18:40


All times are GMT -4. The time now is 16:50.