# 3D Velocity profile

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 November 4, 2007, 14:15 3D Velocity profile #1 Shamoon Guest   Posts: n/a Hi everyone, I am doing 3d analysis of pipe flow. I want to use a UDF for 3d Velocity Profile of Turbulent flow. Can anybody help me how to make that UDF. I found UDF but only for 2d. Thanks

 November 5, 2007, 02:46 Re: 3D Velocity profile #2 Sujay S Guest   Posts: n/a Two thing you can do (1) directly write out the profile and apply (2) or you can write the radial averaged axial vel profile through TUI. and curve fit it to the best polynomial then you can write a UDF using that polynomial function. cheers Sujay S

 November 5, 2007, 13:57 Re: 3D Velocity profile #3 Shamoon Guest   Posts: n/a yes, you are right but the problem is not for the polynomial, the problem is with the 3d geometry! I wnt to use the velocity profile at the pipe inlet. So i ahve to use a 3d profile. Whatever profiles I have seen are for 2D. If we have a parabolic velocity profile in 2D it will be Parabolied in 3D

 November 6, 2007, 01:24 Re: 3D Velocity profile #4 Sujay S Guest   Posts: n/a I got your point. I feel that you can write out the profile from that location and apply to the inlet. It will automatically take care of 3D (i.e. x,y,z co-ordinate values.

 November 7, 2007, 02:25 Re: 3D Velocity profile #5 Shamoon Guest   Posts: n/a Not clear please specify "....you can write out the profile from THAT location and apply to the inlet..." and explain

 November 7, 2007, 02:43 Re: 3D Velocity profile #6 Sujay S Guest   Posts: n/a from where u r getting the profile data? experimental or u r going to run a case similar to u r s and gonna get a profile to apply to the actual case?

 November 7, 2007, 05:34 Re: 3D Velocity profile #7 Emad Guest   Posts: n/a Hello you can 3D velocity profile inter data by using fllowing step2; 1. after read your case and run this case in constant velosity inlet. 2. Go to file -->write--> profile select inlet face and choose velocity save date in new file you can write any name 3. open this file for example microsoft excel 4. you can change velocity value you need inpou at inlet face. with ragerds emad

 November 7, 2007, 05:37 Re: 3D Velocity profile #8 Emad Guest   Posts: n/a Hello you can 3D velocity profile inter data by using fllowing step2; 1. after read your case and run this case in constant velosity inlet. 2. Go to file -->write--> profile select inlet face and choose velocity save date in new file you can write any name 3. open this file for example microsoft excel 4. you can change velocity value you need inpou at inlet face. 5. go to file --> read --> profile then select your file with ragerds emad

 November 8, 2007, 12:18 Re: 3D Velocity profile #9 Shamoon Guest   Posts: n/a I Want to get a profile and apply to the actual case. Actually I am comparing with some experimental data and in that they have a fully developed flow at the inlet. So i want to use that profile at he inlet. The vel profile normally given as V=U(1-(r/R)^2) -----------> for 2D but which cordiante wil be there in formaula to tell the FLUENT that profile is 3D. I hope u got my point!!! Thanks

 November 8, 2007, 13:14 Re: 3D Velocity profile #10 emad Guest   Posts: n/a hello apply inlet velocity at data type no profile. But you can used appley velocity profile to generate velocity data by using any programs. with best regarts

 November 19, 2007, 23:08 Re: 3D Velocity profile #11 ryan Guest   Posts: n/a This is a code that I created by modifying the 2d velocity profile example in the manual. I have a fully developed turbulent profile (logarithmic), but you'll see what you have to do to make it 3d. You establish a variable r and in my case y and z (inlet is in y-z plane and pipe axis is on the x-axis). Then use y and z to compute the variable r. DEFINE_PROFILE(penstock_inlet_velocity,t,i) { real y,x[ND_ND], rad; real z; face_t f; begin_f_loop(f,t) { F_CENTROID(x,f,t); y = x[1]; z = x[2]; rad = pow(y*y+z*z,0.5); F_PROFILE(f,t,i) = Ucent*pow(1-rad/RAD,N); } end_f_loop(f,t) }

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