# 3D wing (flapping elastically) flexing UDF problem

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February 20, 2012, 11:49
3D wing (flapping elastically) flexing UDF problem
#1
New Member

Join Date: Feb 2012
Posts: 4
Rep Power: 6
Hello, Im trying to simulate the flexing( flapping up and down elastically) of a wing in 3D. But im having problems with the UDF, its just rotating the wing along the x direction instead of updating the y position based on the position of the z position to flap it down. I'd be very happy if somebody could help me with it. Im attaching a picture showing only the wing to help with axis. The UDF im using is as follows:

#include"udf.h"
DEFINE_GRID_MOTION(wing, domain, dt, time, dtime)
{
face_t f;
Node *v;
real NV_VEC (axis), dy;
real NV_VEC (origin);

int n;

/* set deforming flag on adjacent cell zone */

Message (
"time = %f\n", time);

NV_D (axis, =, 0.0, 0.0, 1.0);
NV_D (origin, =, 0.0, 0.0, 0.0);

begin_f_loop (f, tf)
{
f_node_loop (f, tf, n)
{
v = F_NODE (f, tf, n);
/* update node if z position is greater than 0.000
and that the current node has not been previously
visited when looping through previous faces */
if (NODE_Z (v) > 0.000 && NODE_POS_NEED_UPDATE (v))
{
/* indicate that node position has been update
so that it's not updated more than once */
NODE_POS_UPDATED (v);
dy = (0.0271*pow (NODE_Z (v), 2)) + (0.2496*NODE_Z (v)) + 0.1396;
NODE_Y (v) = NODE_Y (v) + dy;
}
}
}
end_f_loop (f, tf);
}

Attached Images
 Capture.jpg (17.8 KB, 63 views)

 February 27, 2012, 02:28 3D flapping wing #2 Senior Member   kunar Join Date: Nov 2011 Posts: 117 Rep Power: 6 Dear djan, i am also trying to do analysis in flapping wing(dragonfly),i draw cad model in catia,and i did mesh in gambit right now i am trying to write udf and compile in fluent ,i dont know how to write, i saw your post i want some help from you i am starting stage only for write udf.kindly guide me

 March 16, 2012, 03:37 #3 Member   Join Date: Mar 2011 Posts: 50 Rep Power: 7 either something wrong with your equation or the way you update ur nodes I think it has something to do with updating the nodes

 March 30, 2012, 11:37 #4 New Member   irfan khan Join Date: Aug 2011 Posts: 11 Rep Power: 7 function probably seem to be parabolic. for flapping, sinsusoidal is required. moreover time varation be also included.

 Tags 3d fluent, dynamic mesh, udf, wing flapping

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