# How to create non-uniform velocity profile in FLUENT?

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 September 12, 1999, 12:43 How to create non-uniform velocity profile in FLUENT? #1 pankaj Guest   Posts: n/a hi! I am a new user of FLUENT.I will be grateful if somebody tells me how to apply & create non-uniform velocity profile as boundary conditions. thanks.

 September 12, 1999, 13:12 Re: How to create non-uniform velocity profile in FLUENT? #2 Allan Zhao Guest   Posts: n/a Hello, there are a few ways to create non-uniform velocity profile as boundary conditions. If you know the Graphical User Guide, you can go to create boundary panel. There are three velocity components to input (u,v,w). Below each input bar, you will see a defaut "constant" input request. You can change that to piecewise, polynomail or harmonic profiles. After you click each of these choices, next step will be straightforward to you. Good luck. Allan

 September 13, 1999, 15:08 Re: How to create non-uniform velocity profile in FLUENT? #3 Demselles Hollowajiawoak Guest   Posts: n/a You could write a profile and read it into Fluent example from the menu pick read profile ((profile_vel_inlet 4) (x 0 0 0 0 ) (y 0 0.25 0.5 0.75 ) (x-velocity 0 0.5 0.5 0) ) Note: the 4 represents the total number of points in the profile. When you set the boundary condition and choose the correct profile, fluent interpolates the values so if your grid is unstructured your profile does not have to match the grid locations. regards Demselles

 October 3, 1999, 12:24 Re: How to create non-uniform velocity profile in FLUENT? #4 Marco Bonizzi Guest   Posts: n/a Hello, I'm writing to you from Italy.As FLUENT/UNS user I just can tell you that, in order to use a non-uniform velocity profile, you should do it by a FORTRAN routine. Unfortunately I cannot tell you anything else. Best luck!

 October 21, 1999, 05:26 Re: How to create non-uniform velocity profile in FLUENT? #5 glenn creten Guest   Posts: n/a Dear Marco, I have used non-uniform profiles for velocity and other scalars. I think the easiest way to create these profiles in Fluent is as I did: First write out your profile at the inlet boundary You then obtain a profile file, which contains vectors of x, y, z, and (e.g.) the velocity components You can read these data in a spreadsheet, e.g. Excel, and replace the velocity components by a function of x,y,z. Then save the altered data as text file, and read this back in into Fluent as profile. Finally, you can then use these profiles as boundary conditions for the inlet. Good luck, Glenn. PS. Can you transmit this to the person that posted the original question, since his mail was not on the discussion forum

 January 4, 2010, 23:43 #6 New Member   ang Join Date: Oct 2009 Posts: 1 Rep Power: 0 Hello, I am new Fluent user. From this forum, I have read the case about using Excel to create the wind profile. However, there are some problems that I need help from guests inside this forum. First, I have tried to write the profile file using fluent and what shows in the excel is only X - vector. How can I get Y and Z vectors results? Another problem is that how can I write a new profile based on the excel file? By using calculation such as wind power law to calculate it? Hope one of the guest inside here can reply me soon. Thank you!

 March 29, 2012, 05:46 Non uniform velocity at inlet of domain #7 New Member   PARESH GUJARATI Join Date: Jan 2012 Posts: 4 Rep Power: 6 First you run the problem with constant velocity and then write profile for that constant velocity input. Now change the input velocity as per your requirement and re-read that profile file and solve the problem.

 Today, 04:52 UDF for inlet temperature #8 New Member   mm Join Date: May 2016 Posts: 24 Rep Power: 2 Dear all I have following UDF for inlet temperature, untill 1300s it takes correct values according to equation, but after 1300s values are higher and not accorrding to equation, like at 1301s it should have value of 405C but in simulation inlet temperature is 621C. I could not find the error in my UDF after lot of try. please check this and guide me #include"udf.h" DEFINE_PROFILE(inlet_temperature,thread,position ) { face_t f; begin_f_loop(f,thread) { real t = RP_Get_Real("flow-time"); if (t <=1300.0 ) { F_PROFILE(f,thread,position) = 379.13 + 0.0005*t; } else if (1300.0 < t && t <= 1500.0 ) { F_PROFILE(f,thread,position)= -1.04289036878969*pow(10,-10)*pow(t,6.0)+ 8.86126436853789*pow(10,-7)*pow(t,5.0)-3.13621260398811*pow(10,-3)*pow(t,4.0)+5.91804640375908*pow(t,3.0)-6.27969461279651*pow(10,3)*pow(t,2.0)+ 3.55273415252714*pow(10,6)*t - 8.37223405676245*pow(10,8); } else { F_PROFILE(f,thread,position) = -9.51538261322402*pow(10,-23)*pow(t,6) + 8.26192751387975*pow(10,-18)*pow(t,5)-2.85237398505875*pow(10,-13)*pow(t,4)+4.97518353700886*pow(10,-9)*pow(t,3)-4.58733775886876*pow(10,-5)*pow(t,2)+ 2.10251137071757*pow(10,-1)*t +3.57252192344954*pow(10,2); } } end_f_loop(f,thread) }

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