diffusion Term for add. Variable

Zaktatir · July 14, 2011, 06:13

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, 08:59

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, 11:14

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, 20:31

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

Zaktatir · July 15, 2011, 04:23

Yes Convective time dependent variable but how?

ghorrocks · July 15, 2011, 07:24

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

Zaktatir · July 15, 2011, 08:11

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

ghorrocks · July 16, 2011, 07:52

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, 10:48

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, 10:51

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..

July 14, 2011, 06:13	diffusion Term for add. Variable	#1
Zaktatir Senior Member Join Date: Jan 2010 Location: Germany Posts: 268 Rep Power: 17	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

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July 14, 2011, 08:59		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	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.

July 14, 2011, 11:14		#3
Zaktatir Senior Member Join Date: Jan 2010 Location: Germany Posts: 268 Rep Power: 17	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..

July 14, 2011, 20:31		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	So can't you just use a convection only additional variable?

July 15, 2011, 04:23		#5
Zaktatir Senior Member Join Date: Jan 2010 Location: Germany Posts: 268 Rep Power: 17	Yes Convective time dependent variable but how?

July 15, 2011, 07:24		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	Add an additional variable, and set it to a transport/convection equation.

July 15, 2011, 08:11		#7
Zaktatir Senior Member Join Date: Jan 2010 Location: Germany Posts: 268 Rep Power: 17	that is what that i did but there exist these diffusion terms in the equation of.

July 16, 2011, 07:52		#8
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	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?

July 16, 2011, 10:48		#9
Zaktatir Senior Member Join Date: Jan 2010 Location: Germany Posts: 268 Rep Power: 17	There are Diffusion Terms in the Transport equation for add. Variabel. And please tell me how to set the Coefficient to zero.

July 16, 2011, 10:51		#10
Zaktatir Senior Member Join Date: Jan 2010 Location: Germany Posts: 268 Rep Power: 17	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..