need help for udf about viscous resistance

lihx

Hi All,

I want to change the viscous resistance varying with time in the porous zone by udf. But when compute the case, the fluent warring that: chip-exec: Viscous_term: wrong return type: void udf function expected. Any one can tell me how I can write the unf for the viscous resistance correctly. Thanks in advance. The udf code I have written is given as follows.

/************************************************** ******************* UDF that specifies a custom mass-fraction weighted conductivity ************************************************** ********************/ #include "udf.h" DEFINE_PROPERTY(Viscous_term,c,t) { real ti; real C_PROPERTY; { ti = RP_Get_Real("flow-time"); C_PROPERTY= .......; } return C_PROPERTY; }