[denis Kim]

hope all is well.
I am a new to the Fluent.
Now i am trying to analysis for sloshing.
But problem happened to me. Tho cylinder motion is quite difficult for me.
the motion for the cylinder is sinusoidal motion towards only one way (x-dir only)with +-40mm, 4hz.
Below is the UDF that i written.
Thank you much in advance.

#include "udf.h"

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

pi = 3.1415;

/* define motion variables */

a = 0.04; /* 0.04m movement amplitude */
w = 2 * pi * 4; /* 4Hz frequency */

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

[obscureed]

Hi Denis,


This looks almost correct to me, except that "vel[0] = a * w * sin(w*time);" will give an amplitude "a * w". I think you intended to write "vel[0] = a * sin(w*time);".


Apart from that, it should be OK. Remember to save .cas and .dat files before you start any Moving/Deforming Mesh case. Use an appropriately small timestep. For a long time, there was a bug in Fluent that crashed when MDM cases with UDFs were closed and reopened -- so use a recent version of Fluent, where it has been fixed.


Good luck!
Ed

[denis Kim]

Originally Posted by obscureed

Hi Denis,


This looks almost correct to me, except that "vel[0] = a * w * sin(w*time);" will give an amplitude "a * w". I think you intended to write "vel[0] = a * sin(w*time);".


Apart from that, it should be OK. Remember to save .cas and .dat files before you start any Moving/Deforming Mesh case. Use an appropriately small timestep. For a long time, there was a bug in Fluent that crashed when MDM cases with UDFs were closed and reopened -- so use a recent version of Fluent, where it has been fixed.


Good luck!
Ed

Many thanks to obscureed,
I tried once again, below message poped up.
Is there any problem this UDF?
Please help me..
===============================================
test2.c
# Generating udf_names.c because of makefile test2.obj
udf_names.c
# Linking libudf.dll because of user_nt.udf udf_names.obj test2.obj
Microsoft (R) Incremental Linker Version 14.00.24215.1
Copyright (C) Microsoft Corporation. All rights reserved.

LINK : fatal error LNK1104: cannot open file 'libudf.dll'

Done.

[denis Kim]

Also, what is meaning of "Remember to save .cas and .dat files before you start any Moving/Deforming Mesh case."

[AlexanderZ]

this error means that you are trying to modify library, which is in use (you have loaded your UDF library in fluent) So you should unload first, than compile.

Best regards

[AlexanderZ]

Originally Posted by denis Kim

Also, what is meaning of "Remember to save .cas and .dat files before you start any Moving/Deforming Mesh case."

File -> write -> case & data

best regards

[denis Kim]

Originally Posted by AlexanderZ

File -> write -> case & data

best regards

Many thanks!!!alexanderZ

best wishes,
Kim