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Old   February 15, 2016, 18:44
Default Electrical conductivity
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walied
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Hi every body :

Hoping that every thing is going well.

i need urgent help please.

-the electrical conductivity and the specific heat in my case is not constant and they are a function of coordinates.

-the problem that the electrical conductivity in the material panel doesn't contains the udf option so how can i define it.

- for the specific heat, is there any way to define it? i know that it can be defined as a function of temperature but is there any way to define it as a function of coordinates?

thanks
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Old   February 16, 2016, 05:50
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Bruno Machado
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Quote:
Originally Posted by walied123 View Post
-the electrical conductivity and the specific heat in my case is not constant and they are a function of coordinates.
You need to create an UDS for the electrical conductivity and define the domains it will be computed.

Quote:
Originally Posted by walied123 View Post
-the problem that the electrical conductivity in the material panel doesn't contains the udf option so how can i define it.
The electrical conductivity should be defined in a DEFINE_DIFFUSIVITY macro and hooked to your UDS in the material panel.

Quote:
Originally Posted by walied123 View Post
- for the specific heat, is there any way to define it? i know that it can be defined as a function of temperature but is there any way to define it as a function of coordinates?
I am not sure about it. Once speaking with a Ansys worker, he said the Cp should be only dependent on temperature, because fluent solver is based on density and need a well established Cp.

If you have a look at here, you will see that neither cell or thread are given to the macro DEFINE_SPECIFIC_HEAT.

https://www.sharcnet.ca/Software/Ans...e_sp_heat.html
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Old   February 20, 2016, 21:26
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walied
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thank you Bruno Machado for your kind replay.

but it still not clear.can you please clear more?

if the electrical conductivity is Lamd=constant_1*x+constant_2*y what should i do to define it?

please can you step your kind reply?

thanks
M.Eid
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Old   February 21, 2016, 15:21
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Bruno Machado
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Quote:
Originally Posted by walied123 View Post
thank you Bruno Machado for your kind replay.

but it still not clear.can you please clear more?

if the electrical conductivity is Lamd=constant_1*x+constant_2*y what should i do to define it?

please can you step your kind reply?

thanks
M.Eid
Hi

the electrical conductivity must be defined as something like this (I am assuming it changes with x and y position):

DEFINE_DIFFUSIVITY(elec_diff,c,t,i)
{
real Lamd, constant_1, constant_2, x, y;
C_CENTROID(x,c,t);

constant_1 = XXXXXXX;
constant_2 = XXXXXXX;

x = C_CENTROID(x,c,t)[0];
y = C_CENTROID(x,c,t)[1];

Lamd=constant_1*x+constant_2*y;

return Lamd;
}


Change XXXXX for the values of your constant. After that, once you create an UDS, you can define this as your diffusivity for the new scalar.
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Old   February 21, 2016, 17:32
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walied
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thank you Bruno Machado for your kind reply

but still there are some questions.

1- does i compile the function as the same way of the UDF compilations?

2- from where can i assign the function to a domain....from the material panel like the UDF or what?


2- there are uds_0,uds_1 and so on............ at which uds can i define the function or i should define a new uds?

THANKS
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Old   February 21, 2016, 17:50
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Quote:
Originally Posted by walied123 View Post
thank you Bruno Machado for your kind reply

but still there are some questions.

1- does i compile the function as the same way of the UDF compilations?
Yes, this is an UDF as any other. you can add the one I provided in your current UDF.

Quote:
2- from where can i assign the function to a domain....from the material panel like the UDF or what?
The diffusivity itself is defined in the material panel. But before define it, you gotta define your UDS (Define -> User Defined Function -> Scalars) and the domains you want it to be solved.

Quote:
2- there are uds_0,uds_1 and so on............ at which uds can i define the function or i should define a new ads?

THANKS
I did not get your question, but if you have more than 1 UDS, you can define an if statement in the diffusivity for different integers (i=1,2,3...)
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