Learning Forum

[ahmed ibrahim]

how to make the same thing such that C_T(c,t) at the centriod in udf in named expression because i have a peoblem in running the udf?

[SRP]

Hi,

Can you please explain what problem you are facing in running UDF?

Thank you

[ahmed ibrahim]

when i run a udf in ansys 2021r2 and above for single precision 
i have

Node 0: Process 15576: Received signal SIGSEGV.

 

==============================================================================

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

999999: mpt_accept: error: accept failed: No such file or directory

 

and in double precision

BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES

 

 

 

[DrAmine]

Does depend on what you want to achieve per UDF? I see you created another thread so please try to answer to that thread!

C_T is just Static Temperature Variable in Ansys Fluent Expression Language

[ahmed ibrahim]

DEFINE_SOURCE(elec_power,c,t,ds,eqn)

{

real x[3];

real ir;

real source;

C_CENTROID(x,c,t);

ir=1.687E+06+31657*x[0]+62239*x[1]-4.902E+08*x[0]*x[0]-1.869E+06*x[0]*x[1]-4.944E+08*x[1]*x[1]+1.008E+06*x[0]*x[0]*x[0]+1.698E+07*x[0]*x[0]*x[1]+6.09E+06*x[0]*x[1]*x[1]-3.391E+07*x[1]*x[1]*x[1]+8.459E+09*x[0]*x[0]*x[0]*x[0]+4.648E+08*x[0]*x[0]*x[0]*x[1]+1.584E+11*x[0]*x[0]*x[1]*x[1]+1.243E+08*x[0]*x[1]*x[1]*x[1]+9.672E+09*x[1]*x[1]*x[1]*x[1];

source=-(0.0144*0.55894609*ir*(((0.21+((-0.002)*(C_T(c,t)-298.15)))*(1+((((2.62323E-23)*(C_T(c,t)))/((1.602176E-19)*(0.93040049+((-0.002)*(C_T(c,t)-298.15)))))*((double)log((double)833)))))-(((0.0263+(0.0000355*833)+(0.00178*(C_T(c,t)-298)))*833*833*(pow((0.009637761+((-0.0007)*(C_T(c,t)-298.15))),2.))))))/0.00000864;

C_UDMI(c,t,0)=source;

return source;

}

this is my udf which i have a problem in ansys

 

so i want to make the same thing in named expression

so i had a problem in defining the cell temperature at centriod in named expression like udf

[ahmed ibrahim]

is that what you mean?

[ahmed ibrahim]

[ahmed ibrahim]

so when i use the same thing in the picture in the equation

it will be read as cell temperature at cetriod for the part i want or not

this is the question

[ahmed ibrahim]

c_t (i want it at the centroid of each cell in the part)

how i can do this in named expression

[DrAmine]

Yes that variable corresponds to the cell centroid static temperature.

[DrAmine]

As you are not liniarzing you can directly provide the source term via Fluent Expressions. Please check your region you are trying to emit the source if it is correct.

[ahmed ibrahim]

 

i swear, you solved a big problem for me 

thank you ftom my heart

but what is the meaning of (not linearizing)

 

[DrAmine]

I refer here to the Customization Manual where DEFINE_SOURCE is explained.

Another good reference is to go through the basics with reading the simple introduction of Patankar "Numerical Heat Transfer and Fluid Flow".

Linearization will help on stability.