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-   -   Vibrating / Deforming Wall UDF (http://www.cfd-online.com/Forums/fluent/32855-vibrating-deforming-wall-udf.html)

Qureshi January 15, 2004 09:11

Vibrating / Deforming Wall UDF
 
After getting the UDF Tutorial running, now I am back on to my problem. I have to study the effects of vibrating membrane (as a wall) in a pipe. I've to make a function and then UDF for that function. ]

Anyone out there working on such problem?

I hope that I get some guideline with it. The tutorials and the UDF users guide are not much of the help as they just identify the basic requirement of a UDF.

ccc January 15, 2004 20:31

Re: Vibrating / Deforming Wall UDF
 
hi Qureshi,

my problem is about vibrating wings, similiar to yours and so, I guess, maybe I can give you some help.

the following is parts of my udf.just enjoy it, ^-^.

DEFINE_GRID_MOTION(wing, domain, dt, time, dtime) {SET_DEFORMING_THREAD_FLAG(THREAD_T0(tf));

begin_f_loop (f, tf)

{

f_node_loop (f, tf, n)

{

v=F_NODE (f, tf, n);

if (NODE_POS_NEED_UPDATE (v))

{

NODE_POS_UPDATED (v);

pos[0]=NODE_X(v);

pos[1]=NODE_Y(v);

pos[2]=NODE_Z(v);

dispz=0.0;// the displacement

NODE_Z(v)+=dispz;

}

}

}

end_f_loop (f, tf)

}

good luck.

Qureshi January 16, 2004 04:48

Re: Vibrating / Deforming Wall UDF
 
Hi CCC, Thanks for posting your part of UDF.

I'll be trying it over the weekend. Just a couple of questions.

Are doing the case for a 3D case, i.e. the whole wing?

I am concerned with a 2D case and may be later on if need be then 3D. Can you elaborate on that?

My case is that a wall vibrates in the first mode of vibration. The max amplitude is around .5% of my wall length. The flow moves over the wall.

A simple sine wave function with a time period from 0 to Pi/2 gives the curve (just an example) or in other words we can have an equation in terms of x for displacement in y dependent on time t and get the displacement, the first derivative would give velocity and the next acceleration. So how can we go about it?

Any ideas or guideline?

I am really greatful to you for your assistance.

Regards,

Qureshi


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