# energy source UDF

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 August 1, 2006, 02:46 energy source UDF #1 Jason Guest   Posts: n/a Hi, I have a trouble about UDF. The energy produced by the chip is varied with time. Anyone can help me modify the UDF? Thanks~~ /* Heat Generation Rate UDF */ #include "udf.h" DEFINE_SOURCE(source, cell, thread) { real T = CURRENT_TIME ; real source ; real s1, s2, s3, s4 ; s1=10E+5 ; s2=5*10E+5 ; s3=2*10E+6 ; if (T <= 0.05) source = s1; else if (0.05< T <= 0.15) source = s2; else if (0.15 < T) source = s3; return source; }

 August 1, 2006, 04:43 Re: energy source UDF #2 Anon Guest   Posts: n/a A source term also needs its derivative. that is missing in all the conditions. Derivative term here is zero since your source is a constant. Units are: W/m3. Please check an example UDF in the manual.

 August 2, 2006, 02:35 Re: energy source UDF #3 Jason Guest   Posts: n/a Hi Anon, I changed my UDF as following but the result is incorrect. Could you tell me where is the error? Thanks! * Heat Generation Rate UDF */ #include "udf.h" DEFINE_SOURCE(heat_source, cell, thread, dS, eqn) { real T = CURRENT_TIME ; real source ; real s1, s2, s3, s4 ; s1=5*10E+7 ; s2=10E+5 ; s3=2*10E+7 ; if (T <= 1.5) source = s1; else if (1.5 < T <= 2) source = s2; else if (2 < T) source = s3; return source; }

 August 2, 2006, 14:30 Re: energy source UDF #4 summer Guest   Posts: n/a You need add the derivative as ds[eqn]=0 since it seems that s1 et.al are constant. Hope it helps.

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