# Convergence

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 January 8, 2014, 07:42 Convergence #1 New Member   amir Join Date: Jan 2014 Posts: 5 Rep Power: 6 hi, I have a question... how can I converge an equation with just a convection term? I don't have any diffusion and unsteady and source terms... does it have any specific discretization?

 January 8, 2014, 09:27 More detail #2 New Member   Marc Join Date: Jun 2012 Location: Glasgow Posts: 8 Rep Power: 7 Can you describe in more detail what it is that you are trying to do? __________________ Marc

January 8, 2014, 12:17
#3
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amir
Join Date: Jan 2014
Posts: 5
Rep Power: 6
Quote:
 Originally Posted by laingmj Can you describe in more detail what it is that you are trying to do?
I use a finite volume code, in the species equation with the simplification I just have a convection term and it is equal to zero.
In this situation my code is running to diverge.

January 8, 2014, 12:49
#4
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Filippo Maria Denaro
Join Date: Jul 2010
Posts: 3,805
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Quote:
 Originally Posted by amirmohammad I use a finite volume code, in the species equation with the simplification I just have a convection term and it is equal to zero. In this situation my code is running to diverge.

Is that something like Div (rho*V) =0 ? that is a constraint, must be satisfied coupling it to the other equations.

January 8, 2014, 12:57
#5
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amir
Join Date: Jan 2014
Posts: 5
Rep Power: 6
Quote:
 Originally Posted by FMDenaro Is that something like Div (rho*V) =0 ? that is a constraint, must be satisfied coupling it to the other equations.
It is Div (rho*U*C)=0.0

C is the concentration of species.

 January 8, 2014, 13:02 #6 Senior Member   Filippo Maria Denaro Join Date: Jul 2010 Posts: 3,805 Rep Power: 42 the key is the same, the convergence of the solution is obtained while solving a system of equations, you can not focus only on this single equation

January 8, 2014, 13:05
#7
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amir
Join Date: Jan 2014
Posts: 5
Rep Power: 6
Quote:
 Originally Posted by FMDenaro the key is the same, the convergence of the solution is obtained while solving a system of equations, you can not focus only on this single equation
I have 5 equations

1) u momentum
2) v momentum
3) pressure correction
4) oxygen concentration
5) water concentration

in water concentration I just have a convection term as follow:
Div ( rho*U*C) = 0.0

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