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-   -   How to patch initial disturbance on free surface (http://www.cfd-online.com/Forums/fluent/49904-how-patch-initial-disturbance-free-surface.html)

Ted Chu November 26, 2008 08:17

How to patch initial disturbance on free surface
 
Hi all,

I would like to know how to patch a wave profile on the free surface as an initial condition. It is a 2D case. VOF is used. Air and water. The wave will go from left to right.

Thanks...


k.baker November 26, 2008 08:24

Re: How to patch initial disturbance on free surfa
 
is it a stratified flow case?

shoushibo November 26, 2008 10:38

Re: How to patch initial disturbance on free surfa
 
you can use DEFINE_INIT macro. by judging the relationship between the y coordinate of the cell and the wave profile you can patch the vof is one

Ted Chu November 26, 2008 12:21

Re: How to patch initial disturbance on free surfa
 
I guess it is a stratified flow case. Air is on the top, and water is on the bottom. Both are fluids. But, correct me if I am wrong..

Ted Chu November 26, 2008 12:33

Re: How to patch initial disturbance on free surfa
 
Thanks shoushibo. By the way, do you have a cas file and the DEFINE_INIT udf which you had patched an initial free surface profile?? I am doing a term project for a class, so kind of in a hurry. Many thanks to you in advance....

k.baker November 26, 2008 13:57

Re: How to patch initial disturbance on free surfa
 
is it a pipe flow? you work currently with 2D or 3D? what you want to predict in addition to free surface fluctuations?

BOHIS November 26, 2008 14:04

Re: How to patch initial disturbance on free surfa
 
Hi there, I think that Mr. Baker knows me very well. Let me say hello to him! :) By the way, if you tend to have smooth initial interface, you should put command (rpsetvar 'patch/vof? #t) in TUI before initialization.

good luck

k.baker November 26, 2008 14:13

Re: How to patch initial disturbance on free surfa
 
Hey Bohis thanks a lot for your reply with this please tell us in which option in TUI this facility to getting smooth free surface was available?


Ted Chu November 26, 2008 22:32

Re: How to patch initial disturbance on free surfa
 
Thank you guys for sharing tips. To answer Mr. Baker's question, I am doing a solitary wave propagation simulation. It is a 2D case. The wave will travel from left to right. The free surface fluctuation will be the only focus. I know how to patch undisturbed free surface into the domain, but don't know how to patch the initial wave profile. shoushibo suggested using DEFINE_INIT. I am trying it now. Do you guys do it differently??

At the mean time, I am moving the left boundary as a wavemaker. But, as we know, it is hard to produce a pure solitary wave this way. The tailing waves always exist.

bohis November 27, 2008 10:31

Re: How to patch initial disturbance on free surfa
 
Hi guys, actually I do not know how (rpsetvar 'patch/vof? #t) really works. rpsetvar is scheme command which sets the variable patch/vof. If you use #t, then the interface will be smooth. If you use #f, it will be sharp. You should type it directly as a command in TUI before first initialization.No more questions about it, I do not know more :) (note: I have never tried it with udf initialization - DEFINE_INIT) As regards patching, you can either create register using adaption panel or if the shape is complicated, then use UDF.

good luck


shoushibo November 27, 2008 10:47

Re: How to patch initial disturbance on free surfa
 
if you need a case about define_init macro ,i can provide,please leave a email.

Ted Chu November 27, 2008 11:17

Re: How to patch initial disturbance on free surfa
 
Thanks shoushibo. I'd really appreciate it. My email address is yutechu@hotmail.com.

Thanks bohis for your input.


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