Hi guys, I'm dealing with a 3d simulation with a udf for export the variables every time step. I want to save the value of density at a certan face of a boundary, in the UDF manual is written that the value of density is only available in the cell center. Do I have to perform an interpolation or anybody knows how to get diretly that value? Tanks

Hi,

You posted a doubt on cfd forum attached below.

I have a similar doubt in my project, if can kindly throw some light on it, i would be highly oblidged.

Thanks, Ravi Bharihoke Chemical engineering student IIT Kharagpur India

Hi guys, I'm dealing with a 3d simulation with a udf for export the variables every time step. I want to save the value of density at a certan face of a boundary, in the UDF manual is written that the value of density is only available in the cell center. Do I have to perform an interpolation or anybody knows how to get diretly that value? Tanks

Ok I solved it in this way: Using the connectivity macros you can get from your face thread and id, the values of the two closest cells. Now you can export the density at the center of these cells. From these values you can interpolate to have the value of the density in the face. Unfortunately this works if the two cells belong to the same fluid zone, if it is not the case I don't know yet how to do it, i'm still looking for an answer.

Hi,

Thanks for your reply.

Pardon me coz I am a novice in cfd.

My doubt is I have a udf with DEFINE_PROFILE(f,t,i) macro .... now i want my udf to return values of velocity and mass fraction at boundary... now since mass fraction is scaler... by what variable name do i define species mass fraction?... i tried by giving F_YI(f,t,i) but it is not working....