[lucifer0226]

Hi everyone,
I'm modeling the process of selective laser melting using FLUENT.And, there are two sets of data of thermal conductivity . in the begining, the thermal conductivity of powder system equals to powder when the working temperature is below the melting temperature and when the temperature exceeds melting temperature the thermal conductivity of powder change to bulk .
I want to know which code could help me implement the function.
thank you

[Kirill-MIPT]

Hello! Does thermal conductivity depend on temperature only?

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[lucifer0226]

Originally Posted by Kirill-MIPT

Hello! Does thermal conductivity depend on temperature only?

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yes,
the effect that i want to achieve is like

if(the temperature of this cell never exceeded melting temperature )
thermal conductivity=powder;
else
thermal conductivity=bulk;
thank you for your reply

[Kirill-MIPT]

Check the udf manual, there is an if/else condition in 2.3.18 for DEFINE_PROPERTY macro in Example 1. It's used for viscosity definition there, but one can use this macro for any physical value

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[lucifer0226]

Originally Posted by Kirill-MIPT

Check the udf manual, there is an if/else condition in 2.3.18 for DEFINE_PROPERTY macro in Example 1. It's used for viscosity definition there, but one can use this macro for any physical value

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i know how to use this, but now i want to make a mark of the cells of which the temperature reach melting temperature.

[Kirill-MIPT]

The first thing that comes to mind is making a list of cells, and if the temperature in a cell reaches the border, one puts a boolean value in the list, and for each iteration we make such procedure

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[lucifer0226]

Originally Posted by Kirill-MIPT

The first thing that comes to mind is making a list of cells, and if the temperature in a cell reaches the border, one puts a boolean value in the list, and for each iteration we make such procedure

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thank you for your patience
it is what i mean, so do you know which udf code can help me achieve it,
like MPCHG in ansys APDL

[kirmaks]

Hallo, you may use UDM for this, take a look on DEFINE_EXECUTE_AT_END and put some logic there: loop through Your cells in the required region and put "0" or "1" into the UDM.

[Kirill-MIPT]

Check the example in 3.2.6.3 in udf guide and modify it. You may print cell centroids and a boolean (maybe with temperature) in a single macro

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[lucifer0226]

Originally Posted by kirmaks

Hallo, you may use UDM for this, take a look on DEFINE_EXECUTE_AT_END and put some logic there: loop through Your cells in the required region and put "0" or "1" into the UDM.

thank you for your advice ,C_UDMI works well.

[lucifer0226]

Originally Posted by Kirill-MIPT

Check the example in 3.2.6.3 in udf guide and modify it. You may print cell centroids and a boolean (maybe with temperature) in a single macro

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I have used C_UDMI to solve my problem, I do appreciate your help.
THANKS, ANYWAY.

[Kirill-MIPT]

Congratulations! Can I see the code please?

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[lucifer0226]

Originally Posted by Kirill-MIPT

Congratulations! Can I see the code please?

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DEFINE_PROPERTY(thermal_conductivity,cell,thread) /*thermal_conductivity*/
{
real tc,T;
T=C_T(cell,thread);
if(T>=873)
C_UDMI(cell,thread,0)=1;
else;
if(C_UDMI(cell,thread,0)==1){
if(T<=300)
{tc1=237;}
else
{tc1=0.041*T+224.7;}
}
else
{
if(T<=673)
{tc1=5;}
else
{tc1=-284.39+0.43*T;}
}

[Kirill-MIPT]

Thank you!

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