[aar007]

Hi, I am trying to create UDF for my simulation with an initial velocity profile of 65mm at the inlet and velocity of 40m/s. I have tried using the formula below to write a UDF for my rectangular domain but I can’t seem to manipulate the initial velocity at the beginning of the inlet to a have velocity profile 65mm. Below is a copy of my UDF, domain description, and the experimental description of what I am trying to achieve at the beginning of my inlet.

NOTE: I am able to achieve the desired 65mm velocity profile at the desired location(of 4m from the inlet) but not at the inlet.


Formula U=Uref(z/Zref)gamma
Uref=40m/s
Z=z(height of domain 1.32m)
Zref=65mm


Domain
https://ibb.co/G3dxqTP

Designed velocity profile at the inlet
https://ibb.co/ZfLmqkF

[AlexanderZ]

1. For this case you can use expressions, but not UDF from fluent 2019 version
2. Also yo may use profile, which contains velocity vs coordinates.
3. I don't see your UDF, but you need DEFINE_PROFILE macro. You can apply it to any external boundary. Hook it to your inlet boundary as velocity, it should work