# UDF_parabolic velocity profile

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 February 22, 2011, 06:28 UDF_parabolic velocity profile #1 Member   ThanhToan Join Date: Sep 2010 Posts: 47 Rep Power: 7 Hi All, I am studying fully developed flow in tube by using UDFs. The inlet face is on the X-Z plane and the velocity is parabolic profile and normal to the face in the Y direction. After I run some iteration, I checked profile velocity at inlet boundary condition. However, I did not see parabolic profile at inlet condition. Below code as following: #include "udf.h" /* must be at the beginning of every UDF you write */ #include "math.h" DEFINE_PROFILE(inlet_y_velocity,thread,index) { real y[ND_ND]; real z,x,r; #define R 1.615 /* Radius of geometry at inlet region */ #define V 36 #define n 1 face_t f; begin_f_loop(f,thread) /* loops over all faces in the thread passed in the DEFINE macro argument */ { F_CENTROID(y,f,thread); x=y[1]; z=y[2]; r=pow((pow(x,2)+pow(z,2)),0.5); F_PROFILE(f,thread,index) = V*((3*n+1)/(n+1))*(1-pow((r/R),(n+1)/n)); } end_f_loop(f,thread) } There are somethings wrong here? Anybody help me.

February 22, 2011, 09:26
#2
Senior Member

Amir
Join Date: May 2009
Location: Montreal, QC
Posts: 739
Blog Entries: 1
Rep Power: 14
Hi,
I think here's the problem:
Quote:
 Originally Posted by trantoan2008 F_CENTROID(y,f,thread); x=y[1]; z=y[2];
try this:
Quote:

 February 22, 2011, 09:49 #3 Member   ThanhToan Join Date: Sep 2010 Posts: 47 Rep Power: 7 Hi Amir, Thanks for your help. According to your instruction, I check accuracy inlet boundary condition. It's obsolutely accuracy. Best Regard, Tran Toan

 Tags parabolic velocity, udfs

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