
[Sponsors] 
August 21, 2011, 08:59 
Udf of circular edge: Help is needed

#1 
Member
anonymous
Join Date: Feb 2011
Posts: 44
Rep Power: 5 
I have a 2D channel that its edge is circular. I am moving the walls in y direction and this working. However, when I am not able to move the circular edge. This is the UDF I am using...
#include "udf.h" #include "mem.h" #include "dynamesh_tools.h" /* Constants */ #define b 1.5e3 #define T 20 #define a 0.0e3 #define a1 10e3 #define b1 0.5e3 #define R 0.5e3 #define phi 3.1415926535897932384626433832795 #define L 50 #define EdgeHeight 1.0e3 /************************************************** ***/ DEFINE_GEOM(outlet,domain,dt,position) { Thread *tf = DT_THREAD (dt); face_t f; Node *node_p; real x, y; int n; SET_DEFORMING_THREAD_FLAG (THREAD_T0 (tf)); begin_f_loop (f, tf) { f_node_loop (f, tf, n) { node_p = F_NODE (f, tf, n); if (NODE_POS_NEED_UPDATE (node_p)) { NODE_POS_UPDATED (node_p); x = NODE_X (node_p); y[0]=sqrt(fabs(pow(R,2)pow((xa1),2)))+(b1+CURRENT_TIME/T); y[1]=sqrt(fabs(pow(R,2)pow((xa1),2)))+(b1+CURRENT_TIME/T); NODE_Y (node_p) = y; } } } end_f_loop (f, tf); } 

August 21, 2011, 09:45 

#2 
Senior Member

Hi noa,
there are some inconsistencies in your code! maybe you mean: real x, y[2]; y[0]=...; y[1]=...; NODE_Y (node_p) = y;// you have to assign it with a scalar not vector, y[0] or y[1]
__________________
Amir 

August 23, 2011, 09:24 
More help....

#3 
Member
anonymous
Join Date: Feb 2011
Posts: 44
Rep Power: 5 
Hi Amir,
Thank you very much for your help. My model is built from half circle at its edge. every x has two y values. However, when I change my udf and define y as vector, its not working since Node_y gets scalar only. #include "udf.h" #include "mem.h" #include "dynamesh_tools.h" /* Constants */ #define b 0 #define T 20 #define a 0.0e3 #define a1 10e3 #define b1 0.5e3 #define R 0.5e3 #define phi 3.1415926535897932384626433832795 #define L 50 #define EdgeHeight 1.0e3 /************************************************** ***/ DEFINE_GEOM(outlet,domain,dt,position) { Thread *tf = DT_THREAD (dt); face_t f; Node *node_p; real x, y[2]; int n; SET_DEFORMING_THREAD_FLAG (THREAD_T0 (tf)); begin_f_loop (f, tf) { f_node_loop (f, tf, n) { node_p = F_NODE (f, tf, n); if (NODE_POS_NEED_UPDATE (node_p)) { NODE_POS_UPDATED (node_p); x = NODE_X (node_p); y[0]=sqrt(fabs(pow(R,2)pow((xa1),2)))+(b1+CURRENT_TIME/T); y[1]=sqrt(fabs(pow(R,2)pow((xa1),2)))+(b1+CURRENT_TIME/T); NODE_Y (node_p) = y[0]; } } } end_f_loop (f, tf); } Thank you 

August 23, 2011, 09:46 

#4 
Senior Member

Hi,
you can use a ifclause or a compatible statement like this: real y; y=NODE_Y(node_p)/abs(NODE_Y(node_p))*sqrt(fabs(pow(R,2)pow((xa1),2)))+(b1+CURRENT_TIME/T); Bests,
__________________
Amir 

August 23, 2011, 09:56 

#5 
Member
anonymous
Join Date: Feb 2011
Posts: 44
Rep Power: 5 
I am sorry to bug u again but still I am not sure I got it.
I wish I could use IF but in this case of the half circle I have 2 y for every x and there is not a If statement I can use. I didn't understand why u used y=NODE_Y(node_p)/.... Thank you 

August 23, 2011, 10:08 

#6 
Senior Member

Ok, every x has 2 y (in circular arch one + and another ) right?
so you can use if clause (if y>0 then ... else ....) Or, because the difference is just in a negative mark use such compatible mode.
__________________
Amir 

August 24, 2011, 01:23 

#7 
Member
anonymous
Join Date: Feb 2011
Posts: 44
Rep Power: 5 
Hi Amir,
Thank you for your respond. I can't use If statement since that half circle is not located on the X axis, its moving along the Y axis. Thank you, sarit 

August 24, 2011, 03:12 

#8  
Senior Member

Quote:
It doesn't matter; I just wanted to show the procedure; you can use both methods in this case as well. Here you have to know movement of the interface between 2 y. Suppose the interface moves with this function f(t); then you can substitute this instead of 0 in ifclause. Anyway, if you can post your geometry and your desired moving function, I may help you better. Bests,
__________________
Amir 

August 24, 2011, 04:55 

#9 
Member
anonymous
Join Date: Feb 2011
Posts: 44
Rep Power: 5 
Hi Amir,
My files are attached. Thank you for your help, sarit 

August 24, 2011, 07:00 

#11 
Member
anonymous
Join Date: Feb 2011
Posts: 44
Rep Power: 5 
I tried to do that, but than I get that the parts don't connect smoothly, even when the mesh is denser.


Thread Tools  
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
parse error while interpreting udf  Kristin  Fluent UDF and Scheme Programming  3  March 15, 2012 07:43 
fluent add additional zones for the mesh file  SSL  FLUENT  2  January 26, 2008 11:55 
Star mesh import problem  chris1980  OpenFOAM Other Meshers: ICEM, Star, Ansys, Pointwise, GridPro, Ansa, ...  20  May 8, 2006 01:07 
UDF for 3D circular inlet  Wong Wai Loong  FLUENT  1  February 16, 2003 03:39 
UDF...UDF...UDF...UDF  Luc SEMINEL  FLUENT  0  November 25, 2002 04:03 