# UDF velocity profile

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 June 6, 2015, 17:41 UDF velocity profile #1 New Member   will Join Date: Jun 2015 Posts: 2 Rep Power: 0 Hi, I'm simulating a case in FLUENT with a domain of 5x5x1 km³, for micositing of wind turbines. I'm trying to enter a velocity UDF defined as logarithmic profile in two surfaces, which is described below. My problem is that the profile it results is basically a constant speed profile for the two surfaces I'm entering the UDF. I did a quick research for other threads that could help, but I can't solve my problem. Any help would be appreciated, thanks! #include "udf.h" DEFINE_PROFILE(velocidade_log,t,i){ real x[ND_ND]; real z,Uf=0.43,k=0.4,zo=0.13; face_t f; begin_f_loop(f,t){ F_CENTROID(x,f,t); z=x[1]; F_PROFILE(f,t,i)=(Uf/k)*log(z/zo); } end_f_loop(f,thread); }

 June 6, 2015, 17:50 #2 New Member   will Join Date: Jun 2015 Posts: 2 Rep Power: 0 Oh nevermind, I found the problem. This one below works if anyone is interested #include "udf.h" DEFINE_PROFILE(velocidade_log,t,i){ real x[ND_ND]; real z,Uf=0.43,k=0.4,zo=0.13; face_t f; begin_f_loop(f,t){ F_CENTROID(x,f,t); z=x[2]; if(z<0) z=z*(-1); F_PROFILE(f,t,i)=(Uf/k)*log(z/zo); } end_f_loop(f,thread); } sircorp and soheil_r7 like this.

January 10, 2016, 03:13
Environmental Monitoring. CFD-technology. UDF-function
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Kuptsov A.I. "Environmental Monitoring. CFD-technology. UDF-function ". - The scientific journal "Vestnik teknologicheskogo universiteta", №20 - 2015, p. 203-207;

UDF unstable atmospheric stratification

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UDF neutral atmospheric stratification

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UDF stable atmospheric stratification
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and UDF source term

Kuptsov A.I., Akberov R.R., Islamkhuzin D.Y., Gimranov F.M. Numerical modeling of the atmospheric boundary layer with the account of its stratification // Fundamental research. – 2014. – No.9. – P.1452-1460.

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 #include "udf.h" #include "mem.h" #include "flow.h" DEFINE_SOURCE(xmom_source_K, c, t, dS, eqn) { real y, x[ND_ND]; real source; real mut = C_MU_T(c,t); C_CENTROID(x, c, t); y = x[1]; source = -0.00367*(-9.81)*(-9.81)*mut/(0.85*1005); dS[eqn]=0; return source; }

 Tags fluent - udf, logarithmic, velocity