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Old   November 15, 2012, 07:19
Default Adding and resolve a differential equation
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Luigi Gurreri
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I have a transport equation of a scalar C in which it appears another (vectorial) variable i.
Also I have a differential equation of i: div(i)=0.
Can I introduce and resolve this equation in Ansys CFX, or it supports only algebraic equations?
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Old   November 15, 2012, 15:50
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Chris DeGroot
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Yes you can add additional transport equations in CFX.
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Old   November 16, 2012, 04:52
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Luigi Gurreri
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The problem is that I haven't a transport equation, but an additional differential equation to be solved
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Old   November 20, 2012, 16:50
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Bruno
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Well, \nabla\bullet\textbf{i} = 0 is also a transport equation. Do you mean you want to solve only this equation and not the others?

If that is the case, you can add and the following Expert Parameters to your simulation:

Code:
FLOW: Flow Analysis 1
  EXPERT PARAMETERS: 
    solve energy = f
    solve fluids = f
    solve turbulence = f
  END
END
You can also go to 'Insert > Solver > Expert Parameters > Model Over-rides' and disable other equations you see fit.

Cheers
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Old   November 21, 2012, 05:51
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Luigi Gurreri
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I have a transport equation of the variable C, in which there is a term containing i; also, I have the equation div i = 0. So, I have a system of two equation. I don't know how I can solve the latter equation
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Old   November 21, 2012, 06:29
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You have four variables (C, ix, iy, iz) but only two equations. Aren't you missing two extra equations to close your problem?
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Old   November 21, 2012, 07:05
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Luigi Gurreri
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I think you're right! Maybe I need others equations. I will study better my problem
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