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 ahvz June 3, 2013 04:57

temperature profile variation -UDF

Does fluent allow the external temperature function to be defined "by branches": i.e. one equation for 0<t<10000s and another for t>10000s for example. This way, the fitting would become much easier with distinct equations for distinct branches of time…

I have this code but it has only one fitting curve equation, while I have two equations for distinct times. how to do this ?

Code:

```/*********************************************************************** udfexample.c UDF for specifying transient temperature profile boundary condition  ************************************************************************/ #include "udf.h" #include "mem.h" DEFINE_PROFILE(Temp_Profile, thread, position)    { real x[ND_ND];                                      real y; real theProfile; face_t f; begin_f_loop(f, thread);  {  F_CENTROID(x,f,thread);  y = CURRENT_TIME;      theProfile=(283.7656)+25.44573*exp(-0.5*((y-49657.42)*(y-49657.42)/(11529.66*11529.66)));  F_PROFILE(f, thread, position) =theProfile;  } end_f_loop(f,thread) }```

regards,

 ousegui June 10, 2013 14:11

Quote:
 Originally Posted by ahvz (Post 431583) Code: ```/*********************************************************************** udfexample.c UDF for specifying transient temperature profile boundary condition  ************************************************************************/ #include "udf.h" #include "mem.h" DEFINE_PROFILE(Temp_Profile, thread, position)    { real x[ND_ND];                                      real y; real t1; //time whre your equation profile changes real theProfile; face_t f; begin_f_loop(f, thread);  {  F_CENTROID(x,f,thread);  y = CURRENT_TIME;    if(y

 ahvz June 10, 2013 15:10

thank you very much

 ahvz June 17, 2013 19:07

I tried to change the domain of my temperature profile by defining time limits:

but the results are very strange. is the code written properly ?

Code:

```/*********************************************************************** udfexample.c UDF for specifying transient temperature profile boundary condition  ************************************************************************/ #include "udf.h" #include "mem.h" DEFINE_PROFILE(Temp_Profile, thread, position)    { real x[ND_ND];                                      real y; real t1=32399; real t2=89999; real t3=118799; real theProfile; face_t f; begin_f_loop(f, thread);  {  F_CENTROID(x,f,thread);  y = CURRENT_TIME;    if(y<=t1)         theProfile=(-3e-12*pow(y,3.))+(1e-7*pow(y,2.))-(-0.0004*pow(y,1.))+(282.08);       F_PROFILE(f, thread, position) =theProfile;          {     if(t1<y<=t2)       theProfile=(-3e-13*pow(y,3.))+(7e-8*pow(y,2.))-(0.0055*pow(y,1.))+426.51;       F_PROFILE(f, thread, position) =theProfile;       }       {       if(t2<y<=t3)       theProfile=(-2e-12*pow(y,3.))+(6e-7*pow(y,2.))-(0.0587*pow(y,1.))+2143.9;       F_PROFILE(f, thread, position) =theProfile;       }       {       if(y>t3)       theProfile=(-4e-13*pow(y,3.))-(2e-7*pow(y,2.))-(0.0301*pow(y,1.))+1881.6;       F_PROFILE(f, thread, position) =theProfile;       }  } end_f_loop(f,thread) }```

regards,

 str6073 July 23, 2013 07:55

hi

I need a udf for a work.I'm quite new in this area, so i really need your help. i need a linear varying temperature profile boundary condition to be applied on a circular face of a cylinder. temperature varies from 25 to 50 degrees from bottom to top of circle. diameter of circle is 470 mm . can you please help???

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