# Variable mass flow at boundary

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 November 20, 2003, 08:01 Variable mass flow at boundary #1 Dimitrios Guest   Posts: n/a Hi fellow Fluent users... As I'm new to this software, everything feels and is strange.....my newest problem though is that I have a boundary with variable mass flow rate due to changes in area. Can I specify this variation in Fluent or do I have to do it in another way?

 November 20, 2003, 08:52 Re: Variable mass flow at boundary #2 ap Guest   Posts: n/a You can implement it using UDF. Hi ap

 November 20, 2003, 09:03 Re: Variable mass flow at boundary #3 Dimitrios Guest   Posts: n/a Thanks a bunch ap

 November 20, 2003, 09:13 Re: Variable mass flow at boundary #4 mateus Guest   Posts: n/a Hi! Your Udf shoul look something like this (it's an axample from udf fluent documentation - for variable velocity inlet) /************************************************** ******************** unsteady.c UDF for specifying a transient velocity profile boundary condition ************************************************** *********************/ #include "udf.h" DEFINE_PROFILE(unsteady_velocity, thread, position) { face_t f; real t = CURRENT_TIME; begin_f_loop(f, thread) { F_PROFILE(f, thread, position) = 20. + 5.0*sin(10.*t); } end_f_loop(f, thread) } regards MATEUS

 November 24, 2003, 10:20 Re: Variable mass flow at boundary #5 Dimitrios Guest   Posts: n/a Don't they have a similar thing for variable mass flux inlet among the udf examples?

 November 26, 2003, 14:05 Re: Variable mass flow at boundary #6 co2 Guest   Posts: n/a I wish they had examples to serve all our research problems ! life would be so easy then !

 November 27, 2003, 02:24 Re: Variable mass flow at boundary #7 Dimitrios Guest   Posts: n/a You don't say? LOL