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-   -   Comet - air velocity (http://www.cfd-online.com/Forums/cd-adapco/54119-comet-air-velocity.html)

Tony Campbell October 26, 2004 15:13

Comet - air velocity
 
Hi folks, Using the post-processing command (plfi vel), in a air water interface problem, i see both the velocity vectors for air and that of water. i guess because the air is lighter, air speed is higher and the vectors have a huge compared to that of water (this is the required vel). i was wondering if there is a way of getting rid of the air velocity at the air-water interface. any help would be greatly appreciated.

probably there should be a way of using the concentration parameter, but i cant figure out how!

thanks for your continued help!

emmanuel November 3, 2004 15:00

Re: Comet - air velocity - have same problem
 
i have the same problem..anybody with any ideas??

4xF November 7, 2004 07:57

Re: Comet - air velocity
 
I guess that you have a huge smearing of the volume-fraction over there or that you have not converged correctly within every time step, which would explain why you'd have such big differences in the velocities. Anyway... If you want to get rid off the air velocity for the display and if SP1 is the volume-fraction of water in air (i.e. Sp1=1 => 100% water), here is the Cometpp macro you need (please feel free to improve...) For the command details, RTFM

%% load velocities into register 1 to 3 stlo 1 u & stlo 3 v & stlo 3 w %% load species 1 into stack 4 stlo 4 Sp1 %% multiply velocity with Sp1 => water only stma mult 1 4 1 stma mult 2 4 2 stma mult 3 4 3 %%% display popo all new vect popo all add edge deco coun on 'Vel. [m/s]' plex

Have fun...


emmanuel November 10, 2004 03:37

Re: Comet - air velocity
 
superb! it works. thanks.


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