# Velocity profile out of a duct

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 April 13, 2018, 05:04 Velocity profile out of a duct #1 Member   Marcello Asciolla Join Date: Apr 2018 Location: Italy Posts: 43 Rep Power: 8 Good morning, I do not know if this is the right section, but I am looking for material (books, notes, papers, ...) on the development of velocity profile out of a duct. Let's consider a fluid inside the duct with a velocity profile and a generic value V on the axis of the duct and out of the duct the fluid is at rest. I imagine that there is a distance from the outlet where the fluid has a flat velocity profile equal to 0. How can I calculate this distance? Are there any matemathical models?

 April 20, 2018, 17:25 #2 Senior Member   Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,665 Rep Power: 65 A laminar or turbulent jet? This is the classical mixing layer problem. Tennekes and Lumley's "A First Course in Turbulence" devotes a good part of chapter 4 to this topic. For the axissymmetric laminar jet, Landau produced an analytical solution. Another important distinction is whether the exit of the pipe is flush mounted onto a wall or not because the jet entrains the surrounding fluid. If there is a wall blocking the entrainment, the solution becomes harder.

 April 21, 2018, 12:22 #3 Member   Marcello Asciolla Join Date: Apr 2018 Location: Italy Posts: 43 Rep Power: 8 For the moment I need a simple evaluation of the order of magnitude, so maybe the solution for an axissymmetric laminar jet could be good enough. I do not know if I have to expect a big difference if there is turbulence, I will check this too. Thank you very much! I will read the chapter 4 of that book.

 Tags duct, profile, velocity