Hi,Guys

Can anyone help me to use UDF to define a moving wall? Thanks

Yes, if you know how to do a UDF it is easy - You use a DEFINE_PROFILE(name, thread, i)

If you don't it will be something like this:

DEFINE_PROFILE(moving_wall, thread, i) {

face_t f;

begin_f_loop(f, thread)

{

F_PROFILE = 10; /* insert speed of wall here, I have used 10 */

}

end_f_loop(f, thread)

}

I haven't compiled it, but it will be pretty similar to that.

hi Big Stone,

Can you make your problem more clear? Does the wall move in the direction parallel or perpendicular to itself? For different cases, the method is totally different.

good luck.

Thanks for Andrew and ccc advice, Actually I want a wall move as sin(t), but I could not find a Macro for wall moving. Andrew and ccc, can you give me more details. Thanks

hi big stone,

which direction does the wall move in, parallel or perpendicular to itself?

if parallel, Andrew's method is ok. However, if perpendicular, you have to refer to the dynamic mesh module in fluent6.1. If it's your case, i would like to tell you more.

good luck.

Hi, Ccc

thank you very much. my case is that the wall move perpendicularly to itself, the wall move sinusoidally with time like sine function. the magnitude of the wall moving is small. Could you give me more details? I know little about UDF. Thanks.

BTW, Andrew method can only be used to define a boundary not for a moving wall? can you try it. Thanks

You can use the UDF I suggested and hook it into the momentum part of the define -> wall boundary condition panel. Select moving wall, absolute and traslational and you can specify how the wall moves in the X, Y and Z directions. This will not chage the flow geometry, it will simply impart momentum onto the fluid adjcent to the wall, so if the magnitude of the movement is small compared to the flow gap this method may should work fine.

hi big stone,

Andrew is right. Since the magnitude of moving is samll, Andrew method applies and may be more effective comparing to dynamic mesh.

good luck.

Hi,

Maybe I mislead you guys. I want to define a specific velocity for the wall. the problem is that I can not find a macro for defining wall velocity as I said to you in last poster. Thanks

Big Stone.

I am struggling the think of a way of making the expanation clearer. Have you made a UDF before? There is no define function for wall velocity, just as there is no define function for, say, inlet velocity or wall temperature, which are created using UDF's very easily. You have to use a DEFINE_PROFILE and hook it into the wall velocity section in boundary conditions in the fluent GUI.

Hi, Andrew

Thanks I got it.

[AYOUB]

Dear Andrew

I was wondering if you could help me how to update the speed of the frame of reference regularly?

Thanks

[vavnoon]

which direction does the wall move in, parallel or perpendicular to itself?

if parallel, Andrew's method is ok. However, if perpendicular, you have to refer to the dynamic mesh module in fluent6.1.

[/QUOTE]

Dear friends,

Could anyone please clear me the direction of wall motion? What is the difference between parallel and perpendicular direction?

I do appreciate it.

Best regards

[AlexanderZ]

for more information on UDF for dynamic mesh read Dynamic mesh chapter in Ansys Fluent Customization manual

[hatim elassad]

Originally Posted by ccc
;110715

hi Big Stone,

Can you make your problem more clear? Does the wall move in the direction parallel or perpendicular to itself? For different cases, the method is totally different.

good luck.

hello everyone,
I want to create UDF code for moving wall perpendicular to flow direction
can you help me with this, please