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-   -   a qestion about CFX4 and CFX5 (http://www.cfd-online.com/Forums/cfx/19219-qestion-about-cfx4-cfx5.html)

cfxbeginner October 10, 2002 10:18

a qestion about CFX4 and CFX5
 
Hello everyone! I know that there is "additional variable" in CFX5.I can set additional variable in the domain and set a additional variable source subdomain. It represents concentraction, like smoke or dye disper in the flow.From it we can see how flow distribute. I wonder if there is similar function in CFX4 or not. How to set it?

Thank you very much!

Astrid October 11, 2002 02:03

Re: a qestion about CFX4 and CFX5
 
Similar to CFX 5, you can define a USERSCALAR. This can represent your smoke for visualisation purposes. You have to set the physical properties (e.g., diffusivity) carefully so that you don't violate with reality. Check the manual on USERSCALAR.

Astrid

lego October 25, 2002 08:01

Re: a qestion about CFX4 and CFX5
 
If you take a look in the manual of CFX-5 Solver and Solver Managaer / Mathematical Models and Solution Algorithms / Additional Variables (page 268) you can find the equation handle tha additional variables. By setting the kinematic diffusivity (Dfi) by the thermal diffusivity [m2/s] and the Schmidt-number (Sct) by the turbulent Prandlt-number it is exactly the heat diffusion equation.

I used it for solving weight factors for thermoelement with which the coolant of a heated rod bundle is measured. If you use heat transfer you can calculate for only one rod by one run. With additional variable you can calculate 20 rod by one run (20 is the maximum number of additional variables).


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