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Old   September 2, 2015, 16:31
Default Source Term
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Fabricio
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I would like to know how is the more practical way to insert a source term as like in the attached figure. The simulation will be transient.

Thanks
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Old   September 2, 2015, 17:28
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Source term into what equation ?

Separately, may I ask what that expression is trying to model ?
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Old   September 2, 2015, 19:57
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Dear Opaque.

Thanks for your contact.

This is the entropy generation equation, that it has two terms, the temperature and friction terms.

It's a volumetric term and I don't know hos is the better way to implement it.

Thanks.
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Old   September 3, 2015, 09:29
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thank you for the explanation about the source term.. Interesting.

If you need the component of the gradient of a variable in CFX, you can use CEL expressions to access them following the syntax

<Variable Name>.Gradient <Component>

For example, you source term can be written as

Code:
EntropySource = ConductionSource + FrictionSource

ConductionSource = Thermal Conductivity * ( (Temperature.Gradient X)^2 + (Temperature.Gradient Y)^2) / Temperature^2

FrictionSource = Dynamic Viscosity * ( 2 * ( Velocity u.Gradient X ) ^2 + 2 * (Velocity v.Gradient Y) ^2 + ... ) / Temperature
Then, in the subdomain definition select the source for the additional variable you defined, and set

Code:
Source = EntropySource
Source Coefficient  = < A value if needed to help convergence >
Hopefully, the source is well behave and requires no/minimal relaxation.

Good luck..
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