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energy imbalance ,Urgent????

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Old   January 17, 2007, 09:15
Default energy imbalance ,Urgent????
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Hello all;

How can fluent compute energy imbalance in each cell?

Thanks in advance for everybody answer me.

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Old   January 17, 2007, 14:01
Default Re: energy imbalance ,Urgent????
Ralf Schmidt
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isn't that the energy residual???

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Old   January 18, 2007, 04:10
Default Re: energy imbalance ,Urgent????
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Thank you;

Ok, But i do'nt know that your definition is really an explanation of energy imbalance based on my definition .

I define energy imbalance as follows;

Initially , if you consider energy equation according to the following relation(without energy source):

{ D(rho*E)/DT+div.[ rho *U* (E+p/rho)-div.[k ( grad(T))]=0.0} (k is effective conductivity , rho is density and div indicates to the divergence operator)

Then,in any iteration according to the discretization schemes:

Energy imbalance = (Unsteady term+ Convection -diffusion)/cell volume ;or; Energy imbalance = [D(rho*E)/DT+(sigma on cell faces) {rho *U.dA* (E+p/rho)}-(sigma on cell faces) { k *grad(T).dA}]/ cell volume ;that dA is cell face vector & U is Velocity vector on the cell face and grad indicates to the gradient vector operator.

Is this same energy residual based on your definition??

How can i access to energy imbalance through UDF(or energy residual)?

Can you present an UDF that compute upper expression?

Please help me.

With the best regards.

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Old   January 19, 2007, 03:57
Default Re: energy imbalance ,Urgent????
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Hello !

I correct energy imbalance in previous message:

Energy imbalance = D(rho*E)/DT+[(sigma on cell faces) {rho *U.dA* (E+p/rho)}-(sigma on cell faces) { k *grad(T).dA}]/ cell volume

I finded that residual is equal to a_p*phi_P+sigma (a_nb*phi_nb)-b that (a_nb is cell neighbors coefficients ;a_P is cell coefficient and b is source term).

It sounds that Energy imbalance= energy residual/cell volume.

Is'nt it ?

Also, i wrote a UDF for energy imbalance .

Would you like see that part of udf which computes energy imbalance ? It is a c file .

would you like i send it for you?

Energy imbalance is very great in some cell's.

Why ??

Please answer me.

I am appreciated for any help.

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