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-   -   diffusion Term for add. Variable (http://www.cfd-online.com/Forums/cfx/90570-diffusion-term-add-variable.html)

 Zaktatir July 14, 2011 05:13

diffusion Term for add. Variable

Hello,
How can i get ride of the diffusion terms in the transport equation for additional variable. I am trying to transport number density like entity but in the theory there are only Source terms on the right hand side of the equation.

Thx Jessica

 ghorrocks July 14, 2011 07:59

I do not understand what you mean.

Do you want to have a transport equation with no diffusion? Just select the transport equation option for the additional variable in this case.

 Zaktatir July 14, 2011 10:14

i am using this transport equation but there exist the diffusion term.
In fact i want to implement an equation like this for the Droplet number Density

(dN/dt)+(dUi.N)/(dxi)=Source

that means without effect of the turbulent diffusion..

 ghorrocks July 14, 2011 19:31

So can't you just use a convection only additional variable?

 Zaktatir July 15, 2011 03:23

Yes Convective time dependent variable but how?

 ghorrocks July 15, 2011 06:24

Add an additional variable, and set it to a transport/convection equation.

 Zaktatir July 15, 2011 07:11

that is what that i did but there exist these diffusion terms in the equation of.

 ghorrocks July 16, 2011 06:52

What diffusion terms? There are not diffusion terms in the convection additional variables. And even if there are, why not just set the diffusion coefficients to zero?

 Zaktatir July 16, 2011 09:48

There are Diffusion Terms in the Transport equation for add. Variabel. And please tell me how to set the Coefficient to zero.

 Zaktatir July 16, 2011 09:51

including both laminar and turbulent diffusion... in the theory of the transport equation for the number density of droplet, bubbles and other particles, no diffusion terms and included..

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