[ana86]

Dear Foamers,



I want to simulate a deforming wall in 2D. The deforming depends on the temperature gradient, and I used the macro
C_T_G(c,t)[0] for the gradient in x-direction. But when I want to use this in the deforming equation, the simulation stops and fluent window closes.

I tried a simulation in 3D and it works.

Can anybody help me?



Thank you!

[sanketdange2007]

Could you please post your UDF for 2D?

[ana86]

Sorry for forgetting to post the udf.



#include „udf.h“

DEFINE_GRID_MOTION(deformingmesh,domain,dt,time,dt ime)
{
Thread *tf = DT_THREAD(dt);
face_t f;
Node *v;
real NV_VEC(dx);
real T, gradTx;
int n;
SET_DEFORMING_THREAD_FLAG(THREAD_T0(tf));


begin_f_loop(f,tf)
{
T = F_T(f,tf);
gradTx = C_T_G(F_C0(f,tf),tf->t0)[0];

f_node_loop(f,tf,n)
{
v = F_NODE(f,tf,n);
dx = 0.0001 * gradTx;
NV_S(dx, *=, dtime);
NV_V(NODE_COORD(v), +=, dx);
}
}
end_f_loop(f,tf);
}

[AlexanderZ]

DEFINE_GRID_MOTION(deformingmesh,domain,dt,time,dt ime)

,dt ime) in your code has space?

best regards

[ana86]

Originally Posted by AlexanderZ

DEFINE_GRID_MOTION(deformingmesh,domain,dt,time,dt ime)

,dt ime) in your code has space?

best regards

Thank you, but that is just a mistake I made, when I copied the udf to this forum.

[AlexanderZ]

ansys fluent customization manual
there is a chapter: DEFINE_GRID_MOTION
with example, which maybe you use as a basis of this UDF

what is the difference between that code and yours?

gradTx = C_T_G(F_C0(f,tf),tf->t0)[0];
dx = 0.0001 * gradTx;

gradTx is a scalar
dx is a vector
this could be the problem

you've told

I tried a simulation in 3D and it works.

that was other UDF isnt it?

best regards

[ana86]

Originally Posted by AlexanderZ

ansys fluent customization manual
there is a chapter: DEFINE_GRID_MOTION
with example, which maybe you use as a basis of this UDF

what is the difference between that code and yours?

gradTx = C_T_G(F_C0(f,tf),tf->t0)[0];
dx = 0.0001 * gradTx;

gradTx is a scalar
dx is a vector
this could be the problem

you've told
that was other UDF isnt it?

best regards

Thank you, that's wrong, of course. But unfortunately this ist not the problem. I also used dx[0], and it didn't work.

In 3D i use the same udf with

gradTx = C_T_G(F_C0(f,tf),tf->t0)[0]
gradTy = C_T_G(F_C0(f,tf),tf->t0)[1]
gradTz = C_T_G(F_C0(f,tf),tf->t0)[2]

[AlexanderZ]

this is a problem, fix it

best regards

[ana86]

Originally Posted by AlexanderZ

this is a problem, fix it

best regards

What do you mean? dx and dx[0]? I fixed it and it does not work.

[AlexanderZ]

how did you fix it?
change x to x[0] ???
its not a solution

best regards

[ana86]

Ok, maybe I made a mistake...



But now I tried in 3D again the following code and it doesn't work anymore...



#include "udf.h"


DEFINE_GRID_MOTION(grid_motion,domain,dt,time,dtim e)
{
Thread *tf = DT_THREAD(dt);
face_t f;

Node *v;
int n;
real NV_VEC(dx);
real NV_VEC(DX);
real NV_VEC(gradT);
SET_DEFORMING_THREAD_FLAG(THREAD_T0(tf));
NV_D(DX, =, 1.e-9,1.e-9,1.e-9);
NV_D(gradT, =, 0.0, 0.0, 0.0);

begin_f_loop(f,tf)
{

gradT[0] = C_T_G(F_C0(f,tf),tf->t0)[0];
gradT[1] = C_T_G(F_C0(f,tf),tf->t0)[1];
gradT[2] = C_T_G(F_C0(f,tf),tf->t0)[2];

f_node_loop(f,tf,n)
{
v = F_NODE(f,tf,n);

if(NODE_POS_NEED_UPDATE(v))
{
NODE_POS_UPDATED(v);

NV_V(DX, *=, gradT);
NV_V(dx, +=, DX);

NV_S(dx,*=,dtime);
NV_V(NODE_COORD(v), +=, dx);

}
}
}
end_f_loop(f,tf);
}



if I neglect the line NV_V(DX, *=, gradT); it works.

[AlexanderZ]

try

NV_D(gradT, =, C_T_G(F_C0(f,tf),tf->t0)[0], C_T_G(F_C0(f,tf),tf->t0)[1], C_T_G(F_C0(f,tf),tf->t0)[2]);

instead of

gradT[0] = C_T_G(F_C0(f,tf),tf->t0)[0];
gradT[1] = C_T_G(F_C0(f,tf),tf->t0)[1];
gradT[2] = C_T_G(F_C0(f,tf),tf->t0)[2];

also Im not sure about tf->t0 part, try THREAD_T0(tf) if previous change is not a solution

best regards

[ana86]

Thank you for your help. I tried both solutions, but unfortunately it still does not work :-(

[AlexanderZ]

check what value C_T_G returns

best regards

[ana86]

I checked, or rather I tried, but fluent also breaks up the simulation. Maybe there is something wrong with my setup...

[ana86]

Hey Alexander,

I found the error. I made a mistake in the setup. Sorry for that... And thank you for your help !